Okay, i think this can be explained by newer devices (mu2000ex) upgrading the xg/gm/gm2 patches, but deliberately leaving the tg300b patches alone, so that the gs midis sound the same. an mu50/80 would sound much closer.

So s-mu2000 now has a fully translated main display. this helps a lot.

It also now plays back a very nice 4 port midi cover of Necrofantasia, complete with all it's display trickery.

Also, you can switch it to "mu-basic" using the system control panel to play back most old files that do not sound correct. this does not lose the new instruments, but simply undoes the changes the mu100 made to the basic GM instruments.

For example, the new much heavier distorted guitar goes back to what it was on the mu50.