Originally I wondered why anybody would spend money for the satelite devices, my phone usually worked and I had a ham radio. I used Bubbler on my phone for tracking. Then I started getting farther out into the hinterlands and there was no cellphone or ham radio repeater coverage. While Bubbler is supposed to store a lot of waypoints with the paid version there were often gigantic holes in the data sent to Spotwalla.
For my piece of mind I bought a Garmin inReach Plus for the tracking and two way messages before going to Canada last summer. Didn't take too long to get it working with Spotwalla. I went Hyder, Watson Lake, Fort Laird, Fort Nelson, and back down through Calgary. Once I left the major cities I was out of cellphone range. The inReach never missed a tracking point the entire trip. Bubbler and the phone being out of range were essentially worthless until I would get to a hotel and connect to WiFi. Many times Bubbler wasn't as accurate as I would have liked.
Family and friends told me they used the inReach Spotwalla link because it was more accurate. Everybody felt better that I was moving and not stuck somewhere. Knowing I could push a button in an emergency and had two way messaging made the trip less stressful. The phone with Bubbler is a nice backup, I prefer using the inReach for tracking after using it several more times on trips.
I compared both Spot and inReach plans along with coverage and other features. For my purposes it costs me $28 a month for the inReach Recreation Plan and I'm happy with it.