I think this is everything you'll need and it seems to work without the rest of my emacs config, but you can also submit an issue or email me as kate on tupl.es (and yes, that's a horrible DB joke) if you have trouble and don't want to continue the discussion here.
(Her actually.) It's M+ 1mn Light (M+ fonts, Type 1, monospace). I think the whole family is attractive & readable and for programming on OS X I wanted something with a lighter font weight (it's got 5) to compensate for OS X's overly heavy rendering of light text on dark backgrounds. For Linux/BSD terms I tend to use either the medium weight or use monofur.
You're welcome. I never think of it as an obscure font family so I didn't list it, but I guess it's not so well known. I can see what you mean about high-dpi though Regular is still a bit too heavy for my tastes, I've just spent too many years on linux terminals that render light-on-dark much lighter. I run at 12-14pt in iTerm2 on a low res 13" mbp, so that may make a big difference as well.