have tried the recent..last 5 years pro co rats and the BYOC blows them away...also sounds like the original one I had...but stupidly sold..many moons ago
I remember in the early 80s seeing Rats queued up in 2nd hand shops for next to nothing, and I never even bought one of them :(
I just noticed that Keeley don't supply modded Rats any more because the build quality is so poor, and they have once again changed the IC that they use.
Happily I have a stock of the metal cased chips and 2 unpopulated PCBs in the house. If I ever get around to building a UV exposure unit I will have to knock together some updated boards.