I have quite a few of these devices as well.
They offer the same challenges, but these must be facing upward. So we wear these on our backside top shoulder. Batteries need to be changed and the units can leak ruining the entire SPOT.
They DO NOT float.
We have lost a few of these from dropping overboard when students were checking them. Attach a tether!
So... the other issue is the annual fee, its a bit tricky to stay on top of all these device annual payments. If you don't check in within 30 days they autorenew.
If you lose a unit its a pain in the ass as well.
2015 Never Quit Challenge Preparation
by shawn alladio
, on Flickr