I have a 2000 scrambler 500 and I have used and abused it.
it is no longer stock. I have installed a Hot Seat Performance clutch kit. 39mm Kehin FCR carb, White Brothers e-Series exhaust, and a K&N. the only problems I have had are my own doing... . I am in my third belt (next one is going to be Kevlar), there are a few holes in the plastic (first day out misshap), had to relocate the lights due to a rollover.
One thing to keep in mind... the E brake is hydraulic and will slowly bleed off... . I had a slight problem on sunday when this exact thing happened. We had to use my buddies winch to pull it out of the hole it landed in.
I change the oil every month... . I use Castrol synthetic 10W30, and a Napa Gold filter # 1358... . I will check to make sure that is the right #.
Keep the RPM up, or the belt will smoke, or put a groove in the drive pulley. The only thing I wish the Scrambler had was a low range for those really tight spots.
While I admit that there are many quads out there that are faster... when the going gets really sloppy and nasty, I leave my 400ex and Raptor buddies behind..... (they get me back on the easy stuff)
bottom line
the Scrambler is a great machine, do not neglect it.
-Cliff