I'd go for http://www.findmespot.com/en/index.php?cid=219
I've been using the original Spot device since its inception, before that, it was a lightweight 5-pound EPIRB for ocean kayaking. I'm ready to move up to the next level of this technology.
Reasons are:
Light weight
Most potentially effective communication in face of emergency
When it comes to initiating a life or death SR, it is a bargain for the money
Peace of mind