I was speaking in general. I know a good bit about bikes, but I haven't ridden any of the ones you're looking at so I wouldn't be able to advise you there.

I just looked into them a bit and the two that I would look at are the Radon or the Scott. Upon looking into those two bikes more, I personally would go with the Radon if it were in great mechanical condition. I'd prefer the 26" wheels and I'd feel like the Radon would be a little tougher and perform better than the Scott. Radon is full XT with a nicer fork than the Scott, right? The Scott is rockin a lesser fork, still decent but slightly inferior derailers, a "blah" octalink crankset, Alivio shifters, are those generic Shimano brakes?, etc. It's just generally a step or more below everything on the Radon. If the Radon isn't in great condition, though, that could change things.

EDIT: Nevermind, I just found the bike you're looking at. It's not full XT, but I think I'd still pick the Radon if it were me. See which one fits best and think about what wheel-size you want and the type of riding you want to do. Oh, and I'd offer $500 just to see what the seller comes back with.