Indeed. I witnessed some very lively runs on Paddington / Worcester's with un refurbed 50's in circa 78- 83. Whatever you think about them, love them or hate them, if you got a good one, they could really go like stink! That was certainly my experience with them in the 80's.
The book "BR Motive Power Performance" by David N.Clough & Martin Becket has a very interesting chapter, titled, A Type 4 challenge. A good read if you can find it!
It is said that "when running properly, Class 50 can beat any other Type 4 in all respects".