When CatalystG made the pcsx-rearmed port for BB10 I was quite extatic. I’ve kept using it even after he dropped support for it when Retroarch came out simply because I was so far into a game and was unsure about save file differances. well now I really want to move over to retroarch as i would be able to play on my various differant devices by keeping my save on cloud storage.
The question. What do I need to do to get the .mcd file from pcsx for BB10 converted to a usable format for retroarch?
I had to convert a GBA save from the gba.emu so that it would work in retroarch vbanext.
http://forum.themaister.net/viewtopic.php?id=812
I am not sure if that program will convert all retroarch save files for all cores or not though. Based on the source name I would imagine it only works on GBA games. I only had to compile and use it for a GBA game I was playing which was in .sav format. You can certainly try it though. It is super easy to use. I just dropped my GBA save file onto that .exe and it spit out a save file retroarch vbanext could use in the .srm format.
I also do what you do. I use dropbox as my save location and on android I use dropsync along with dropbox to keep my game folder in sync so that I can play my games from my nVidia Shield, Tablet or phone using the same saves.