well, i believe almost every post in here is wrong or not complete, sorry guys. but you are. both are good all around quads. i ride a shee for everything. its all in the setup. as long as you maintain the bike CORRECTLY it wont cost much to maintain or rebuild. now a trx 250r does handle MUCH better than a shee, hands down. they both make great trail quads. the 250r shines in just about any situation you put it in. the shee lacks in certain areas. great for drag racing, yes. goin fast and wide open, yes. turning tight turns, no. flattrack, probly cant beat it. its all in the setup guys. ive even had my shee on an mx track, it did ok, but my new project will be less work.
problem with the shee is the suspension geometry isn't made for great handling, so often times you use your body weight and the throttle to control your turning, which in most cases is more of a power slide.
both are great quads, all about preference. if you decide on the shee, i know where you can get a great portjob done on it, thats dyno proven (1 setup dyno'd at 63hp with slipping clutch, stock stroke, fmf pipes, pump gas, not much more than that either. still has some tuning room), and fast. PM me or 370 for more info.
the trx250r is probly one of the most sought after quads. its one of if not the most winningest quads ever built. quads today are modeled after it. it was made to race, any race. they build power quick and easy, are pretty cheap to build, and the 400ex has the same frame, so parts interchange. so you can still find parts just about anywhere. and they too , depending on setup can do anything you want it to.
hope i helped with a little more in depth info. have any more questions, i'd be glad to help. i've ridden both, and have both here at my house....