I have ridden both and prefer the 1500 over the 1800. It just rides better. It also has hydraulic valve lifters. I think the problem with the 1500 alternators is mostly the rear bearing. If it goes bad it spins in the case and ruins the case and is quite common I guess. The nice part is it takes an hour or less to change it. The Compufire alternator puts out 90 amps but it's $500+ (with the new agm battery).
The power of the 1800 is unbelievable and it is often called an "old mans crotch rocket"
All that being said, if I am alone or going 100 miles or less, I get the 83 out. It's just plain more fun to ride and it even sounds a little bit like a motorcycle.