IMO the reason PLB's aen't as popular as they should be is that on land, other gear can be used for the same function and also be used doing everyday things. A cellphone is self explanatory, they're used everyday and are extremely common. The GPS I like to carry (that Garmin Geko I linked to) can be used any day for hiking. There are places that you won't get a cellphone signal and in those areas the cellphone/GPS combo isn't much good, but since getting lost is one of the emergencies people have in the wilderness, the GPS is a really good fix for that -- stay found and you won't need to get found.