If you're creating music-related startups or software, you're probably better off getting a .fm domain, since it is easier to find good domains there and users are accustomed to it.

Funny enough, I actually considered some of the terms you suggested (my software fades out music when you play a video) before I started thinking about .fm. The obvious problem with the terms you mentioned are that they are long, difficult to spell, and obscure to non-musicians.