Some '03's had engine failure problems. I don't know about other years, but I know of several that failed & it seems I have heard it was due to a spacing issue with the cranks (dunno). I only heard about failures in '03's & this was in race bikes (stock engines, though). May not be an issue for street use.
A friend that has an '02 & '03 (no engine problems for him) tells me that his '03 is stronger. Maybe the engine in the '02 in more 'tired', I dunno.