Well being able to tweak the XO is one of the best parts of DIY. If you want a bit stronger or weaker mids or highs you can just adjust it a bit.
Having said that I haven't heard the (Aviano8/Mezzo6). I've heard some Dali speakers and they were pretty fantastic they were however over $2000 per pair. I don't remember what Monitor Audio speakers sounded like as its been too long, and every pair of Wharfdale speakers I've heard just didn't sound all that good to me.
To put it into prespective, I have a friend who has a pair of these.
They were MSRP $1000 a pair, he got them for $800 I believe. Then I built a pair of these for $200.
Everyone agrees, they sound 99% as good as the Triangles. The Triangles have a bit more bass but you can always just use a sub.
So you can see the value of DIY. If you pick a good design that costs almost $1000 per pair to build none of the speakers you're looking at should even be able to touch it.
As for your diy selection I don't know much about the GR-Research kits, nobody really talks about them anywhere for a few reasons.
The ZDT3.5 should be fantastic. They do need a decent sized room to really play well, you're supposed to sit at least 2.5 meters away from them or more for the sound to really blend.
The ZRT 2.5way Revelators should be incredible. I've got a friend who is probably going to build a set very soon but so far I can't speak about them from experience. I haven't read any reviews online from anyone who built a ZRT or ZDT3.5 and wasn't completely satisfied with them.
There is also the Zaph Waveguide TMM to consider, the Statements and quite a few other designs.
Just look at this big list of DIY speaker web sites.