i say tr450, then the yeti.
reasoning:
light, simple, burly on both bikes. I'd take the transition over the yeti because it's a bit more maintenance free (no need to worry about the rail), and it's a really good company IMO. geo numbers look just about right, and you can't go wrong with a linkage driven single pivot. that, and they look sick.
reason to go for the yeti: adjustable geometry gives you a bit more flexibility, especially at somewhere like fontana, where the courses change often enough to justify a geo change from time to time.
also, iirc the yeti's pivot is a little higher up than the 450's, so that should equate to a bit more rearward axle path and better square-edge performance (shock rates aside)
I'd steer away from the V10 for everyday riding. based on my experience on the M6 (another xtra long travel VPP bike), it doesn't jump well, it doesn't like to be juked around too much, it just wants to go in a straight line down the hill (which it does amazingly well). not exactly the best type of bike for socal riding IMO.
hit me up this weekend and I'll gladly talk DH bikes with you. :thumbsup: