That leaves about 8400 levels that use another music file though.

If you disregard the official music, which falls in the category "used to death" for me, there are a lot of technoish tracks on top. Of course this is partly because that kind of music is a lot more suitable for tracking than more "melodic" pieces, but such a one-sided music selection does indeed get boring fast. While there are certainly good modules out there, a large part of those used often (Elwood's, for example) are cheesy, generic or simply not good... but then again, you might like such songs, after all music is a matter of taste.