Hi! Ill try to answer your questions as best I can.
1. That the tubes are described as unmatched may mean that they are from different manufacturers, or they may be from the same manufacturer but have not been batch-tested to ensure that they have identical electrical characteristics. One often sees ads in audio magazines for matched pairs or matched quads of a given tube, selling for significantly more than 2 or 4 unmatched tubes would go for. Theoretically, a matched set of tubes has been tested electronically and certified that their electrical characteristics are identical, or nearly so. Theoretically, this is supposed to guarantee better sound. Personally, I have never bothered. I ust make sure that when I re-tube an amp, I replace all of the tubes at once, rather than in piecemeal fashion.
2. Unfortunately, I have had no personal experience with MITs, so I cannot comment except to say that published opinions in the audio press are widely divergent. Some swear BY them, others swear AT them!
3. Colins comment reminds me of something else. Mac amps generate more tube noise than most other tube amps. While you should not hear the sort of scratchiness that he describes - and if you do it means that something is wrong, usually one or more bad tubes, but sometimes failing passive components as well - when Mac tube amps are hooked up to K-Horns, with their 104db sensitivity, you hear a constant, low-level hissing sound, even without any input from source component. This has never been an issue for me as I have found that a soon as I start playing music, the low-level hiss is almost completely obscured by the music (except e.g. in the quiet moments of classical music). Given your stated preferences in music, this should not be an issue for you, but I wanted you to be aware of it so that when you hear it you wont think that something is wrong.
4. Given your stated preferences in music, IMHO you might be better served by the MC-30s. The gutsiest 30 watt amps you are ever likely to experience. Especially when driving K-horns, they sound more like 130 watt amps. Absolutely no lack of - how shall I say it - testicular fortitude!
Hope these comments help. Again, good luck!