The motors, as long as they recieve pretty basic maintenace, are surprisingly tough and can do high miles without any problem.
As long as you keep up the belt change schedule and the valve clearances they'll run out to 100K easily.
The electrics are good, mostly the issue you'll have is people not routing the wiring properly and maybe older wires getting a bit stiff.
My S2R is happy as a piggin', press the button and it goes. LOL Love to say step on the brakes and it stops but the rear is always an issue. It can be more of a decorative item (except for MOT time) but then I don't find that I use it very much. Some say the front calipers are budget jobs (true) but they work .. maybe not as well as they might but more than well enough.
Any weakness is in the suspension, the rear isn't too good and the front isn't either. I've got an andretti misano conversion to go in when I can get around to it for the front and I'll end up with a new rear. I did have something to compare with that says the S2R could be heaps better but then you'd expect a race homologation 758R to handle a little better
