Ultimately, I decided to order the Jawbone Era. The main competition is the BlueAnt Q2. The Amazon reviews are what really threw the decision for me. Professional reviews from various web sites, don't go into the same level of detail.

I made the decision based on people's reports of comfort (several were unhappy with how the BlueAnt feels), noise cancellation (several reports that the Jawbone is superior), and of course size (it's the smallest -- I need something that can disappear into a pocket, since I refuse to be one of those people who walks around all day with a thing in their ear even when they're not on the phone).

Sigh.