I had the 73rd '01 Raptor off the assembly line waaaay back when they first came out. I loved riding the thing after I flipped the rear linkage to lower the rear end a bit to help with cornering. I did mostly trail riding so the little loss of travel didn't affect me any. But, as was said, the early transmissions were JUNK. I rode mine for a year (hard) before the tranny started acting funny and I decided to trade it in on a yz426f. A friend of mine bought one a few weeks after I did and put a total of 3 or 4 transmissions in it in a few years time. I'd have probably kept it had it not been for the shitty tranny.
I can't comment on the newer ones, though.
However, I can comment on the yzf450 quads. A couple friends of mine have those and those things are fucking sick. Granted, they're mostly aimed towards track riding, but they do just fine on trails and fucking get it as is.
And to the Cali boy......dune riding is gay, gay, gay. I've never seen the appeal of driving them in a straight line or drag racing up a hill. Whooptydoo.