We have a couple of problems here TIm.
One is that we are talking to tha converted - pretty much everyone in this forum
understands that transponders do not offer a panacea, and would have major
negative results if mandated for all aviation.
Two is that the propaganda value is against us.

Consider human nature - The transponder issue - is in my opinion another example
of intellectual laziness. Generally speaking people are inherently given to
doing the smallest amount of thinking they can. Our problem here is that is is a
very easy thing to "understand" that if everything in the sky carries a
transponder then we (the general public, sitting in the nth row)will be safe.
Unfortunately this also extends to the bureaucrats occupying the nth desk at
FAA, because it is an easy decision. The FAA types probably do understand the
issues, but from their perspective less random aviation means less risk. In fact
it is easy to conclude that it is actually better for the people who are
resisting this idea, because even if this prevents large parts of a sport from
operating - they are better off not flying, than flying without this technology.
Because we have already accepted that this technology already somehow magically
ensures there will be no mid-airs.

We know that a transponder without human attention is an expensive waste of
panel space. We know that the speed differentials make ACAS etc a nice idea but
unlikely to help in a real emergency. We know there are a few places where a
transponder will substantially improve safety, and by all accounts most glider
pilots operating in those areas have voluntarily started fitting them.

From an intellectual effort perspective all of our arguments are much harder
work. If we want to win this argument we have to present a simpler case.

Maybe one way is to look at the behavioural consequences of a blanket policy of
fitting transponders . The airliners can now "safely" assume that they can fly
point to point at, over any point in the country, and at any time, because
everything in the sky is now visible to ATC. Apart from the assumption about ATC
capacity to monitor and manage, I wonder how many of the general public are
thinking of the intrusion this could mean for them. In this world the airlines
start having the contest finish problem, of aircraft are approaching from all
directions, and need to be sent via a couple of control points to straighten out
the kinks.

Look at it from the positive side, at least the lives of the ALTPs will get a
whole lot more interesting.

When the predictable incident/accident ensues, it is unlikely that the NTSB will
conclude that probable cause included inappropriate behavioural change as a
result of complacency resulting from the mandatory fitting of transponders. Too
many thoughts in one sentence - pilot error is something everyone understands.

The long report that started this looks like someone was actually trying to
understand and explain, and ended up getting edited somewhat.

Tim Mara wrote:
How many transponder equipped gliders, transponder on, have been hit by a
non-TCAS equipped general aviation aircraft? Is this really a problem? Can
it be addressed by training?

does that mean that having a transponder on board will eliminate this risk?
Does that then allow us to feel secure that it can't happen or won't? The
only way even with a transponder installed and operating to know what
traffic is around you is to be in contact with ATC....simply sending a
signal doesn't tell everyone around you that you are there.
tim