I currently use a headworn rig based on the Sennheiser KE4-211-2 omni measurement mics. They sound pretty awesome. If you want an example, see my KT Tunstall recording I have posted on Dime.
http://taperssection.com/index.php/topic,112627.0.html
Also, check out the Countryman B6's...they're fairly expensive but they sound amazing.
Yep the Senns sound great. I've got three pairs of these, one on loan to Steve. Bascially anything you put in front of those mics sounds good. Lots of detail and nice warm sound.
If you want both realistic and great sounding, try the Countryman B3. These mics sound great for both ambient and music, and they have low self noise (24dbA). The only better mic is the Nevaton MKE400, but I've had reliability/consistency problems with these.
I had the B6, and they sounded great, but I had overload problems. I did not try the low sens version. Oh yeah, for ambient recording you can't beat the DPA 4060. For some reason I don't like these for music recording, though. IMO they sound a bit "harsh". Everyone's ears are different. I wish I liked the DPA for music, but I don't.
Richard (still searching for the perfect omni mic...)