While not exactly a PLB, I'm using a Delorme InReach SE unit. It allows web based tracking, two way satellite text messaging and a good SOS features in case you do need a rescue.. Basically it's my electronic tether giving my wife some peace of mind while I wander around the countryside. It also integrates well with my smart phone to make entering messages easier.

The only drawback I find is the cost of the subscription service plan.

http://www.inreachdelorme.com/produc.../inreachse.php