Here are a few of my PRR switchers:
K-Line A5 upgraded with cruise and 4-chuffs/revolution.
K-Line B6 upgraded with cruise and 4 chuffs/revolution.
Weaver C1 upgraded with cruise.
MTH SW-1 with PS-2 modified with the small pickup rollers to prevent hang up on uncoupling tracks.
All are excellent little engines that I will use in my yards (well, the C1 isn't that little). The A5 sounds like a machine gun even at slow speeds, and its great.