I'll second the SNZB-01P. I just fired one up yesterday, and it appears to be performing great.
The form factor doesn't bother me too much. Yes, it's thick, but I appreciate that the footprint isn't any larger than it needs to be to cover that beefy CR2477, and if the battery life is measured in years, then I can live with it.
My only issue was it wouldn't send 'action' packets at first. It paired and re-paired easily, but just wouldn't send the presses. I re-paired directly in front of the hub, away from the hub, changed drivers, holding one leg up, etc, and after about the 3rd or 4th re-pair, it finally started sending presses, and has been fine since. My -02P temp sensors did the same thing, so it wasn't terribly surprising, and it could be something I'm doing on my end.