The cell based solutions are great but I see them complimentary to spot/inreach, and not a replacement. Spot/inreach are pretty consistent in sending updates in fix intervals, typically 10 min, while cell based may have long gaps especially if you fly high or in the desert such as in western US. More importantly, in the event of a crash where the pilot is incapacitated, spot/inreach may continue sending your location, or at least show your last location shortly before the crash.

Ramy