I have to correct myself. Sasq made a replacement bios for the mmc64 which is atleast compatible with some ide64 fixes, and afaik it requires no retro replay. http://www.nightmode.org/mmc/doc.txt

Where did that come from? Those MMC64 plugins use RR as add-on to MMC64, not vice versa.

For "normal" user who just wants to speed up loading majority of his games MMC64 is more useful than RR. Try playing your favorite single-load game with nothing but C64 and RR. Ok, you might be able to do it by flashing it into RR, but to do that...

That way of stating it is fine with me. By the way, which RR RAM banks are used by the MMC64 plug ins? Say I want to use two (16K) for my own program...which should I choose to minimize conflicts (if it's even possible)?

D64 mounter uses first two or three banks, but there is no guarantee it won't use all memory for sector buffers one day.