I have a Spot Messenger 2.
It's not a PLB, EPIRB or whatever else but it does what those things do, in a slightly different way. It also does more..... tracking, ok messages, special message (pre programmed)
I'm happy with mine.
If you have a smart phone, I'd look at the spot connect ... it has the ability to send SMS from the smartphone via bluetooth to the Sat system and to preprogrammed recipients.
I found the lifetime costs to be similar with the spot having more uses for me.
If I'm up in the high country and have a heart attack, stroke or roll off the side of a track I may never have set off the EPIRB/PLB/Spot ... but with the spot it's sent out tracking blips every ten minutes and the last point is a good place to start looking ... I'm somewhere nearby, especially if those blips haven't moved for a while (yes, I might already be dead, but i'd be found before the wild dogs found me) Planned routes often change due to weather, flood, trees down, whims and fancys, closed tracks and breakages etc. Although I always leave info regarding planned routes they have on occasion varied wildly from what eventually happened.
I generally send out an OK message every night at arrival at camp and every morning on departure from camp and possibly another one during the day ... sometimes just to mark a particular place, hut, view or whatever.
Works for me
Stevo