Soaring ought to be about flying the aircraft, not just monitoring the
government-mandated distractions. The thing would either be activated during
most thermaling,

If the problem you're solving is landing accidents, simply disable the
device while the gear is up. If you have fixed gear.....

or have such a close tolerance as to give no useful warning
to those who would most need it

This is a good point. The Skylane that I own a small piece of has a horn
that sounds about 10 kts before the actual stall - and as such, is
pretty useless, IMHO. This is pretty typical for most power planes and
during a normal landing you expect it to go off. The problem with a
close tolerance is false alarms. If the alarm goes off too often due to
gusts, or what ever, a pilot will tend to ignore it when it's really
trying to tell you something.

Dick Johnson feels that a properly designed stall warning works in
gliders. He knows more than I. Still, I can't help but think of all the
power pilots that have landed gear up while the gear warning was
blaring. They were (typically) totally distracted during a high pressure
situation and either did not hear it or failed to grasp its significance.

Tony V.