And for that matter, smartphones know your altitude. A message every
5 minutes that includes altitude would be dramatically more useful
than what we have with Spot 1/2 and only cost $1.20/hr. My Spot
connect should arrive in a couple days. I'll try to assess if there
is a flaw in this idea.

You can always power the phone from the ships battery. I understand
that the Spot Connect unit returns to AA batteries instead of the
stupid AAA batteries that were used in Spot 2 so I wouldn't think that
Spot Connect battery life will be an issue -- Spot 1 lasts quite well
on the AA lithium batteries.