Having used both a SPOT, and a sat phone, on my own time I'll take a sat phone any day.  Yeah, they're expensive, but if you only use it in an emergency, the price is worth it.  Iridium by far beats Globalstar for coverage and reliability (used to be reverse, but I hear G lost a bunch of satellites a few years back, and hasn't replaced them yet).

As for the SPOT, was useful for checking in each day when working in the bush, but also felt like someone was always watching over my shoulder.  I prefer to leave the gadgets at home when tripping. Reliance on a gadget can never  replace good planning and judgement.  (maybe its my invincible youth speaking here!)