With these 2 projects now merging into a single project, MAME and MESS will become a single huge emulator.

Personally I'm not sure. It was nice to have MAME emulating every arcade machine, and MESS attempting to combine and emulate every home system (computer and console). The issue I've always had with MESS is that each machine emulation has been a log way behind each stand alone emulator for each platform.

My biggest question at the moment is the future of MAME as it currently stands. What will happen to the ROM, CHD and Extras sets? We had a big shift and headache when Pleasuredome changed the MAME archive structure some time ago and switched to Merged sets. This was logical because it greatly reduced the size of each archive because it removed the duplicate common files from the rom sets and merged them to share the common files. However with the merging of MAME and MESS will be see the file structure and naming convention change again?

MESS using something called Software List sets. These are XML based sets with all of the ROM data held in these XML file lists, linked to the included rom files. MAME sets as they stand don't do this, but I've noticed that now PD is starting to released Software List Rom and CHD sets for MAME. Do we need to switch to this? Can our existing MAME sets be rebuilt into the Software List sets to join the new torrents? Or can we continue to use the existing MAME set structure?