I'll get to my rant at the end.

First, a question: what happens if you turn off a transponder in
flight? Hypothetically, of course: would anybody notice? Would S&R
be sent out to look?

Second, a recollection: it's my recollection that ATC radar is
designed to filter out slow-moving targets. If that's the case,
transponders are only of any use to TCAD-equipped aircraft.
Apparently some ATC facilities are seeing the glider Xpdrs, so maybe
my recollection is wrong?

Third, evidently I now have a choice between a low-priced TCAD-type
device or a Xpdr. Having both is not an option: my panel is already
full, so stuff has to start coming out in order for me to put things
in.

Fourth, it is NOT illegal for me to turn off the TCAD-type device to
save my batteries, but it is illegal for me to turn of the Xpdr (my
home field is 33 nm from the primary airport). Score one for passive
rather than active collision avoidance. The passive device uses a lot
less power. Score two. The passive device is cheaper. Score three.

Fifth, it seems to me that an Xpdr should be fitted with a separate
battery, so that it doesn't threaten the much more important nav and
vario equipment by draining power from them. Similarly the Xpdr
should not drain the battery required to relight self-launchers.
Legally, I have no idea where you stand when you have a "working" Xpdr
on board, "turned on" but with a dead battery. But it's safer than
the alternative.

Now my rant: bad enough that regulators make dumb laws, but worse when
SSA compounds the error. Here's why -

Regulations that impose requirements on safety equipment that isn't
even required in the first place are logically bad law (not that bad
law is particularly unusual) because they create a disincentive to the
use of safety equipment. It reminds me of the reg about parachutes:
if my chute is past its repack date, it's perfectly legal for me to
use a seat cushion instead and leave the chute in my car. If I take
the chute anyway (as a seat cushion), it's illegal and I can get
busted. My chute's always properly packed (go ahead, check) but
that's not the point. Which of our regulators wants to explain to a
grieving family that the totally unnecessary fatality was caused, not
by the out-of-date parachute (which probably would have worked fine),
but by a regulation that REQUIRED LEAVING IT ON THE GROUND!
Similarly, a regulation that requires the use of a transponder, if
fitted, when transponders are not required, is a regulation that
encourages people to... not fit transponders. Poor logic, bad law.

This request for an exemption suffers from the same faulty logic. The
place where transponders are most important is... around the primary
airports of Class B and Class C airspace. This exemption request
removes the disincentive to carrying Xpdrs everywhere... except where
Xpdrs are important!

Rant over.