All these questions all have to do with how hard you ride. Do rip up every hill you see, are you pegged in every gear possible for long periods of time.
If you keep the bike stock and just cruise around and do your maintenance regularly, that motor could last you a long time. If I'm not mistaken I think someone on here said there wife has had her banshee for 13 years without a single rebuild. My guess is she proly does not ride it to often.