Here it is:
Dramatic battery drain when second headset is plugged in?
nope. battery life on these things is redunkulous. cant get them to die. after 5 hours of non-stop stereo use (flight to vegas) it went from 4 bars to 3. OLED screen with batt indicator is PRICELESS.
Realistic battery life in stereo and mono?
Like I said, i haven't "measured" it to give you a quantitative number, but it frigging long
To me its fine. I dont like in-the-ear gel thingy's. It hooks over my ear and the speaker just kinda sits there not unlike a moto 500. After a min I dont feel it anymore so I'd give it high marks.
Second earpiece have a tendency to want to fall off similar to the original Sony stereo headsets with similar design?
I have no experience with the sony things you're talking about but the secondary ear piece is just a smaller version of the main one. it hooks over the ear just the same and has the same earpiece/speaker/whatever you wanna call it. Do earpieces with loops tend to fall off a lot? I don't know. these don't fall off of me.
Hope this helps a bit. If you wanna buy this headset, and I plan to, just click the picture below.