The reason the MUNT version you have doesn't sound good is because that particular version you're using doesn't synthesize the partials correctly. But besides that it sounds the most like a real MT-32 out of all those tracks you've got there (except ScummVM emu which is the same thing). The newer version in development is much better. Here's a couple recordings from MI1 and QFG1.
These are recordings from back in May. MUNT has come a long way. The reverb still isn't quite the same as a real MT-32, but it's pretty dang close. I don't know if this current version of MUNT is publicly available or not, though.