My wife is of the, "no news, no calls w/in plan window, means he is dying in the desert". (very slight exaggeration).

Before going with SPOT I was heavily swayed by ACR. In fact I still carry a very old, but reliable rubber button ACR Firefly strobe that ran on those lipstick style mercury or lithium cells before I converted it to CR123.

Anyway, I have never seen a dedicated PLB act as a I'm Okay function using the test sequence. Interesting but honestly I think its trying to make something into something it is not. I mean, we do that all the time but somehow to me it feels weird using a test function as a communication function.

SPOT2 messages are sent over several minutes. You could not hit the button multiple times for multiple updates going to the recipient.

What SPOT2 does very well (w/ some learning) is track the unit online. For hiking I usually set up a Shared Page for my wife to see online. When in Track mode the unit pings the website every ten minutes and to make sure there are no gaps, it sends the last one (maybe two) pings to make sure the gap is filled in. This way DW can see where I am at. For some of my routes she knows my exact turnaround (hilltop, river, etc) so she can see right away if I am heading in, heading out, and so on.
Don't just survive. Thrive.