I ran several belt cars (Schumacher CAT series) and several shaft cars (Predator, Lazer ZX5), but now my mind is made up : after the ZX5 i'm going back to belters. I like the smooth power delivery and IMHO a good designed belt car like the Schumacher CAT2000 beats any shaft car in terms of reliability. The original Predator i had was a nightmare and the Lazer was becoming one.
I have a TRF501 on pre-order now. Never liked the XX4 design.