Re:
I have no idea what it is, but you're right it's too nice for a commuter/thrash bike! The drilled drop outs and seat post suggest it was used as a proper racing bike, whatever it is. It would be shame to see it get beaten up much (I've made this mistake myself in the past and now I'm going to have to do a full repaint and rebuild from scratch on a bike I used for a few winters...).
The diamond on the fork crown could be a good clue to someone who knows more than me (presuming it's the original fork, and it looks like it is). It looks like it would be a lovely ride with a bit of TLC, new saddle, new bar tape, etc. Hopefully a fairly minor refurb and you've got a lovely bike. And this is stating the obvious a bit, but don't ride it with the handlebar stem out as far as it currently is - it's making me nervous just looking at it! :?
