i had a big hit 2 and that was what i was on a diablo all last year, but i sold it an am now riding my enduro pro. well, untill i tore my ankle up on the US open weekend.
big hits are popular bikes there, but i am easily more comfortable with the enduro. an sx trail would be awesome. a lot of kids had them there last year. and from what i see of the new sx trails (yuk!) i might be picking one up this season. i need to sell my extra enduro first though.
as for the compnents on the big hit, the fork has sub par travel quality and is pretty heavy. the cranks are going to be problematic. they seem to fall off big hits a lot. but that's just sram crap. the shifters are junk, but they are pretty minimal in the grand scheme of things. rims are going to be alex rims, so they aren't likely to last long.
don't get me wrong, the big hit is a great bike for getting people into the sport. it opens doors to going beyond that, but i'm thinking that you can do better for a bike to take to diablo. people are tearing that park up on 6" bikes just fine. remember that quality is better than quantity with suspension travel. that said, if the big hit is what fits your budget, it is hard to go wrong. beat it for a season and then sell it like i did.