I think there is one bushing that gives trouble - but mainly to the Europeans because they actually ride their GTS's in the rain. If you keep it lubed it's not a problem - and the bearings are cheap anyway.
The guy I bought this one off said people had called and lowballed him, using the cost of a new front rotor ($800) as an excuse. This one is barely worn and most owners don't seem to ride much anyway so that's hardly a good reason. Also, compared to an exhaust system or other major component for just about any modern superbike, $800 ain't too bad. Besides, it's not as if that wouldn't be the same concern for EVERY GTS and factored into the price/value from the start.
Biggest "problem" to me is difficulty of access to the engine and ancilliary bits. Now that I've removed most parts of the fairing (cowlings in Yamaha-speak) and realized it's not quite the chore I had feared, that concern seems to be receeding.