I bought a 2000 YZ 250 last 08/01. The guy had 6 rides on it and broke his foot. Gave him $3300: his payoff at the bank. I came off a kdx 200. I love the low end torque and extra grunt. So far I've added FMF SST pipe/turbine core II silencer, 11oz flywheel weight and Boyesen carbon reeds. The power is smooth for a moto bike and I ride about 70/30 trail/track. So far I've only replaced the renthal handlebars (flimsy:broke on first good hard crash...But then so did my shoulder, two ribs and a lung!!!!) and back fender.
So far no real probs...but I'd follow the reply about extra greese on swingarm/head and the throttle thing: The last thing I remember was being full throttle and pinned to the back of the bike before I attempted the Super Man miss the seat grab move!!
Good Luck!!!
Dennis
P.S. How do you ride? Track, trails, skill level, etc. ? That would make a big difference on the choice. If you mainly ride trails, I'd give KTM 250 E/Mxc a look. They're all set up for trails and have come a long way in the past 3 years re. reliability, handling, etc.