Listening impressions
Note - (repeated from above post for emphasis) Let me be clear up front - This was by no means a fully ideal comparison for all listeners and all setups. Doing a "proper" comparison for all attendees, in ideal locations, with each setup powered and dialed in properly would have likely taken 3-4 full days. With just 1 full day of listening, we had to make compromises in order to get to listen to everything on the list. Well, almost everything.
Another disclaimer - I'll admit I'm a bit biased toward the higher efficiency setups as of late.
With so much to do I didn't get to listen to ALL of the setups as much as I would have liked to. I enjoy talking to other members and vendors as much as I do listening to the gear so that did consume some of my time as well. With that said, I did get to spend some time in the hot seat for a few of the setups. I will share my thoughts below:
Monitor RX8s
These were a list minute addition as Dave offered to bring them down. I'm glad he did as I enjoyed listening for sure. I was still running around the room helping others but listened to a few clips up front and thought "OK - these were probably too nice to start the meet with!" I was most impressed/surprised most with the bottom end of these guys - much more than I was expecting considering their size. Jim Wilson and I were outside and he asked if the subs were really off - that should tell you something.

I didn't get to spend much time in the hot seat, but from the middle of the room they offered a clean and refreshing sound. In terms of dynamics they seemed to be lacking compared to the larger offerings but that is expected. It's hard to say what they would sound like when cranked up to the levels of the others later in the day so I can't comment on that aspect. Last I checked these listed for around 850 each (someone call me if this is inaccurate). In terms of value I'd say they are mid-pack if that price is accurate.
Ascends
It wouldn't be fair to comment on these since I didn't spend too much time in the ideal positions. From what I heard walking around the room, I thought they had a nice laid back sound, but seemed to offer less bottom end than the Monitors.
SVS Ultras
I had spent about a month (on and off some nights) listening to these in my upstairs setup. Upstairs I thought they sounded average and at times a bit anemic to be honest. But when moved downstairs the sound completely changed - more so than I expected. The sound was much fuller and the bottom end was substantially better than the prior two offerings. I saw that some commented these to be "boomy" but I didn't think that was the case IMO. These could easily be run for music for many without subwoofers added in. They have a nice balanced sound (albeit with a pronounced bottom end), but didn't quite hit the "magic" mark for me that some of the later speakers did. Awesome looking speaker overall though.
LS6s
First thought - What a gorgeous speaker. Like the others, I wish we had the time/energy to give these babies several hundred more watts. It was surprising how much less efficient they were vs. specs on paper. I thought they had a huge soundstage and much better off axis response than the prior offerings in this class. Would have liked to had the chance to crank them up with more power - maybe I'll have to visit ufokillerz to do so shortly.

Beast - Thanks for lugging these monsters up our way to share - many including myself enjoyed watching and listening to them - even if not in the ideal scenario.
Legacy Focus SE
My favorite looking speaker of the day. Thanks to Mike for hauling these MASSIVE beasts over to share with us. Being I've spent some time designing my own crossovers, I can appreciate the complexity of these beuties. I spend about 4-5 minutes in the "hot seats" with these during the demo. I concur with many of the other comments in that they are one of the most balanced setups, but did have quite a narrow sweetspot for such a large speaker. Would have loved to have cranked them up some more with proper power. Will have to come visit Mike one of these days soon.
Arx A5
Unfortunately missed alot of the demo time of these as I was running around the house again.
Fusion 8s
We spent a bit of time listening to these upstairs on Friday night - I was/am very impressed! More similar than different than the larger brother SEOS offerings, especially when run with capable subs. Don't expect thundering bass without subs in a home theater environment, but they will play loud and clean for any sane individual and they won't need more than an average receiver to do so. Top 5 value of the day IMO.
JTR Single 8's
I only got in the hot seat for 1-2 tracks of these. I was also impressed with the output and detail for these guys considering their size. Not sure how they would sound without subs, would love to compare them to something like the fusion 10s or fusion 8s in an A/B/C comparison. I can't help but wonder though, for the small difference and price and size, why not step up to the Noesis 228s?

Blind test next, anyone?
SEOS Tempests / Sentinels
I'm going to combine these together because they were/are more similar than different. They both play clean, loud, and clear with very little power required. The one mistake we made I believe was not letting the group experience them full range. This is where they provide the most value and differentiation from the rest of the peers in this group. Extension and output <80hz is fantastic with these guys and wish we would have let them shine in that area. Austin asked a few times during the demo to do so, to which I agreed but got sidetracked by the end. ADD for the loss, lol.
I do believe if these speakers were to sell as a completed offering by an ID company they would be unrivaled at twice the cost to build. Don't expect Noesis level output, but for 95% of the population (especially with proper power) these will blow you out the room. The big advantages here are extension, nice looks (IMO), and extremely high value.
Yorkville U215's
These were one of the last minute additions and I'm super glad they were picked up to share with the group. Many of us (10-11 or so) got to spend a lot more time with them on Friday. They surely aren't going to win any awards in the looks department - although the raw look kind of suits its personality. If you're like me and going to run them behind a screen this isn't as much of a concern vs. a living room user. These are straight no-nonsense, blow your hair back beasts. Again I think I made a mistake by not letting the group witness them full range. After the event (Sunday) I had them hooked up to the EP4000 and the midbass is staggering! Like the Cat's, something that must be experienced in person vs. an online review. Clarity is fantastic, but slightly less detailed than the Noesis and Cat offerings IMO. I'll agree without EQ they are a bit more bright in my room vs. the Noesis and Cats. Awesome, awesome value for what you can buy them for. Hadn't initially planned on it, but now I'm going to look for a 3rd matching center or another pair if I can find them.
Noesis
This was my second time listening to these guys. Like the others have said, when Jeff builds a flagship speaker he doesn't mess around. A phenomenal combination of raw output, detail, and clarity. They can be powered by an average receiver which is a huge plus in not having to require expensive amps to push them. Excellent overall package when combined with something like Jeff S2's.
Cat 12s
As I told Mark, these are the "end game" speaker for me. Favorite of the day with ease. They had absolutely no audible flaws that I perceived. I almost feel like buying these would be "cheating" since I would have no where left to experiment that would not be disappointing.

In full range mode, simply jaw dropping. Well done, Mr. Seaton. They are not inexpensive, but in this case you really do get what you pay for.
KRKs
This was my second time hearing these as well and again I was impressed. It's not an easy task to follow the "kings" of the day and they did not disappoint. Impressive output while remaining totally clear - Ben had them cranked up to reference for a few tracks. Awesome value for the money as they include active tri-amps in each!
Final thoughts - Like I said there really wasn't a bad setup there that I thought performed poorly. The differences in the higher end setups were more subtle than drastic and realistically once EQ'd in a decent listening environment many would sound more similar than different. Like I said above I'm heavily biased toward the high efficiency setups and I'm mostly a DIY kind of guy these days so weight that into consideration when reading my thoughts. My room isn't perfect but I thought it represented many of the setups quite well.
Everyone looks for something specific when they're shopping for a speaker, or designing their own. For me it's a combination of high dynamics, clarity, the ability to play clean and very loud, and strong value. Looks and the extreme levels of detail are of secondary importance to me, personally.
Gorilla's Value picks, full range in no particular order - KRK 10-3, large SEOS offerings if you're willing to DIY (these were not demoed full range but I have listened to these models extensively)
Gorilla's Value picks, with subs in no particular order - Yorkville U215, JTR Noesis 212
Gorilla's favorite of the day - Seaton Catalyst 12C