Well -- I can tell you the 360 is, and logically so -- far more powerful than the 250. A very good friend recently purchased a new '06 wr250. The area we ride (Antelope Valley - Gorman) is strewn with a myriad of terrain, including hill climbs, single track, woods, desert - just about everything (a well known off-roaders mecca) imaginable. After swapping machines for about an hour, he was impressed and disappointed at the same time. Impressed with the overall superiority of the 360. Disappointed, because he couldn't convince me to trade him - even offering me his bike with an additional $500.
There just isn't ANY conceivable situation where his bike excelled - period. Now, my machine, an '02 has several, what I feel - are improvements. Noteably - I installed the decompression cylinder head which results in starting being a pleasure instead of a laborious chore (yes, it's FAR easier to start than the 250 too). Also, I fitted a 10 oz. Steahly flywheel along with Boyesen reeds, a FMF 'gnarly' pipe with turbine core II silencer which I'm currently in the process of evaluating vs the factory 'SPES' pipe and finally vs.the 'Dyno Port' down the line. Outfitted this way, the bike was SO throttle sensitive, that I installed a G2 throttle cam set up (what a joy). The machine just simply does everything asked of it without a whimper. The flywheel allows rock crawling at a snails pace without fear of stalling on some insane precipice, and even then - If for some reason it may stall, kicking it is easier than my sons CR 125.
I've also outfitted the machine with a teriffic 'Baja Designs' headlight which is quite literally a nightsun type piece worth every cent since I do quite a bit of night riding. For suspension I've had the forks revalved (a must IMHO) and installed an 'Ohlins' shock (pricey but peerless). There's other improvements, mostly ergonomic. I also own a KTM which also, just doesn't compare (will be for sale soon) and an XR650 which is an incredible desert machine albeit more than a modicum porky, though fabulous in any case. In my opinion, and considering that '02 was the final year for green sticker legality on open 2 strokes in California. There's simply NO other machine aside from a Service Honda 500 (which I'm eyeing) that provides the power, handling and overall entertainment of the WR360. Shame they're no longer being produced as I'd purchase a new one each and every year.
As far as replacement parts are concerned..I've never had an issue obtaining everything I've ever needed.. Raymond at Halls is wonderfully knowledgeable and Halls is a top notch outfit. So -- If you can locate a decent example, I wouldn't hesitate.
Kindest Regards