> Can I use the very same files from the most recent MAME and play them with retroarch?
From what I understand you're locked into whatever version is in their core. For MAME it could be as many as 10 or 20 versions behind(Possibly more). I can't even tell from their site which version of an emulator is considered their latest core.
For MAME it makes absolutely no sense to use RA considering it's basically extract and go with either ini settings or inserting what you want at command line to be very flexible.
I am interested tho in the CRT-Royale filter, but there's no way I'm installing all that crap just to give it a look.