Nowhere near as good, in particular the ride which is one of the worst on the network. Other than Pacers, never, other than on a Mk4, have I genuinely felt the vehicle I was in may have derailed or have a very serious fault with a wheelset and started to consider going to pull the handle. Whereas the 158 has by far the best ride quality of any UK rolling stock, past (that I've used) or present - they just glide over even the worst old jointed rail. The only other thing that comes close is the Class 221 (specifically), but that's because it's really heavy, the 158 isn't.