That's unfortunate. Darren and I were hoping MESS would take the torch eventually. At any rate, I think you'll reconsider when compatibility reaches >99%.
I think we should take it eventually. But I also think we have a fairly long way to go otherwise before we consider that. The steps as I'd imagine them are like this (not necessarily in this exact order, although #4 obviously goes last):
1) Master cycle-based 65c816 so all operations and memory accesses take the correct number of master cycles
2) Audit SPC700 for cycle accuracy
3) Fix remaining rendering issues (offset-per-tile, range over, tile over, mosaic). Maybe we do just use the bsnes code - there's a fairly compelling story there, but are we willing to completely trash what we have?
4) Once cothreads are added to the MAME core (Aaron is interested, but I don't know what all would be involved), go ahead and schedule the 65c816, spc700, and video correctly
