1. Rick, you will NOT be sorry your bought those SonicCraft drivers; EVERYONE who has heard my systems LOVES their sound, even as complex as it is.
2. I too am investigating tweeters, again. One problem with dome tweeters is some Venetian-Blind Effect, AKA lobing, at the highest audible frequencies. One-inch-dome tweeters need neodymium magnets so that the tweeters are small enough to be spaced close enough to have very little VBE. The smallest, at 2-1/8" square, 1"-dome tweeters I can find so far are these HiVi TN25s, only c. $8 each in quantities from Parts Express...
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=297-408 ...
Another 2-1/8"-square tweeter I'm considering is the Morel MDT-12, but it's lots more expensive at c. $29 in quantities.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=277-060
BTW, I believe most of us would think a $29 tweeter to be NOT expensive, but when one is using 24 (for 8 Bass/MR drivers) or 26 (for 9) or 30 (for 10) PER CHANNEL, $29 each gets quite expensive.
Because insetting them into a frontplate would be much-more time consuming than insetting a square tweeter, I'm unlikey to choose the Tand Band 25-302SH...
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-804
...or the Vifa BC25SC55-04 from Madisound...
http://www.madisound.com/catalog/product_info.php?cPath=45_229_270_324&products_id=8355
...even tho both qualify on height.
3. On cabinet design:
A. If you have the space in your room to place the fronts of the speakers at least, say, 3' away from all walls AND you enjoy the spaciousness that OBs have, use open-baffle. Unless you actively EQ them, probably they'll need some passive EQing, usually called baffle-step compensation, to 'recover' the lower MR and bass frequencies lost to WAC. Of course, that consumes sensitivity, but you'll have that to burn by using multiple drivers. (My 8-driver systems have a 2.83V-into-8-Ohms-@-1M sensitivity of c. 100dB.) As I indicated in one of my e-mails to you, I have rough plans for a new OB LA design that you're welcome to.
B. If you don't have that much space or if you prefer the more immediate, forward sound of front-only-firing speakers, then build closed cabinets. Jeffrey Glowacki has told me several times that the correct cabinet volume for the JG65s is one cubicfoot per driver, but because I never wanted to enclose them, I don't remember if that's a sealed or a ported system. You might ask at
mail@soniccraft.com .
One more thing, everyone--Sonic Craft is now down to one full and one partial cartons of these excellent B/MR drivers, so if you've been considering them but just haven't gotten around to ordering them, do it soon or they'll be gone.