Just got back from the Marietta, GA Taylor roadshow, so I'll offer a few notes on the 900 and K series V braced guitars that I tried out.
I was skeptical about the intonation claim, thought maybe it would be too arcane for my ears, but it's really true. I have a riff I play with open strings up on the 5th and 7th fret, going up to 12 and every note was dead on. I was really impressed with that.
Can't comment on sustain, cause we're in a room with high ceilings with 14 other guys mashing away at the other acoustics, but I did get to go into a quiet room and my little riff has never sounded so sweet.
After I got home, I played the same riff on my 322 and ya know what? My 322 notes are in tune as well, but what was different about the V braced notes I think it has to do with that the V-bracing design results in fewer frequencies clashing and zeroing other frequencies out. It's not so much that the 322 notes are out of tune and the V-braced notes are in tune, it's that there are more varied frequencies coming from the 322 that aren't blending on the precise note. The V-braced notes seem purer and more focused, which is why I suppose the notes ring longer. So it seems after 200 years of X-bracing, Taylor has reinvented how a guitar top should work. Amazing.
A bit of trivia is that all the V-braced guitars have graphite nuts, so you'll be able to spot them in the store. One guy I asked said there are no current plans to put V-bracing in the GC body, that decision would depend on how well it was received on the GAs.
I was pleasantly surprised I could hear a difference, cause my hearing really does suck. If they ever do get around to making a V-braced GC 12 fret, I'm definitely buying.