Well, it all depends on the setup. But stock for stock, they are all pretty close. But you have to consider power to weight ratio. The groung clearance on the XX is awesome for rocky hill climbs. OTD, both big bores are relatively close, just read dirtwheels and they will tell you that, neck and neck in the drags. It all depends on your upgrades. How big are the jumps you hit? IMO if they are big, then go w/ a straight axle, otherwise you'd have to buy shocks for the XX, cuz the fronts arent that impressive. And if you can finance a XX, you can get them around 4500 OTD depending where you go.
2008 700xx; Power Bomb header with power core 4 exhaust, Power Programmer III, pro armor nerfs, prm products control front and rear bumpers and full skid, 10" ITP rears, ITP Baja's fronts, RZR 2's all the way around, Uni filter, 13t sprocket, CCP steering Damper, DS450 shock swap, Dual Gasser Throttle, bar risers and Moose barkBusters. 730XX kit plus other engine mods!