Have to say without know much about any of the bluetooth headsets I lucked out with the 640.
Fit is fantastic, I can run without it falling out and this is without the earloop.
Sound quality is great. I have only used it with the unit on my hip.
Components, AAA charger ***** (5 star), holster/clip haven't had a problem yet, got up to 100mph on motorcyle with clip in my shirt pocket with earpiece in holster. Probably won't do it again
. Already had usb cable from BB to charge. Adaptors great idea. Ear pieces, I use the largest one.
Connection time has not been an issue.
Charge time... usually have a cable nearby or AAA charger. I rotate between a couple rechargable AAA batteries.
Love the vibrate feature when unit is in holster, even works while not charging.
If I lose this one I would definetly get another 640.
Ben