I love mine. It's an 02 Edge X 800. Motor-wise it's all stock except for an MBRP race can, which sounds great. I couldn't tell you about the top speed or any other mods since i've only put on 140 miles. Awesome torque from 30 and up. My boss (who rides an 06 Yamaha Rage) rode it and he said it's got "scary amounmt of torque." I would recommend stretching it at least a 136". Mine's a 144" and I love it so far.
Some guys say that the crank bearing is weak. There is an upgrade for that. The exhaust valves are upgradeable to stainless steel (i think). But like anything, maintainance is huge. Find one that has been babied or low miles and I think you'd be fine. Mine had 1750 miles on it and i got it for $2000, cuz the chaincase was slipping. New chain and seal and I was good to go. I don't think you will be disappointed with either one, 700 or 800.
Good luck in your search.
I need big jugs on my sled, cuz my girl doesn't.
2002 Edge X 800
~M-10, Electric start, 144" x 2" track, PERC, SLP pipe/can, Edge Works rail extentions, homemade tunnel extention, 8" MMP yellow Dagger wheels, Team roller secondary, reversable oil pump, Sidehiller II's, 6"-8" Rox adj. riser, gutted airbox, scratchers, yellow pull handle, yellow mountain bar, Gravity Worx extended throttle cable and brake line, windshield bag, 25/41 gears, 66 gram weights, almond spring.
2007 Dodge Ram 2500
~5.9L CUMMINS TURBO DIESEL, auto, quad cab, short box, B&W gooseneck hitch, silencer ring MIA, torque tube baffles MIA, Smarty Jr, ISSPRO gauges (boost, trans temp & EGT)