BBob
WKR
Yes they did.Backpackinglight.com did some pretty extensive testing of various emergency messaging devices and the difference was pretty obvious on devices using Iridium vs Globastar. Iridium is simply a better platform—especially in dense forest and deep draws; it just makes it easier to acquire satellites.


Gear Guide: Satellite Messaging Devices ("Messengers") - Backpacking Light
This gear guide summarizes the category of satellite messaging-centric devices, i.e., devices that focus on satellite messaging as its primary, rather than secondary, function. This is in contrast to navigation-centric devices (which usually offer integrated mapping on the device), such as the...
