Today I checked the MESS and I can tell you the followings:
- bad interrupt handling (Icicle series do not work)
- very good CPU emulation
- fast disk emulation
- terrible keyboard
- scroll and raster have some bug (Tom 16 works quite good, but the scroll is awful)
- hard to use...
After all, MESS is a very good project, the C16/Plus4 part will be fine. We - emulator authors - have to improve our emulators if we want to do the best.