My experience mirrors P3's.

Had a flight a few years ago where I had to overfly the El Paso Class
C. Phone call the day before, radio contact 10 miles out and all the
way across. They were very polite and helpful.

I have a new glider coming in a few months and I'm really torn on
whether to get a transponder ... my first glider didn't have one, my
current one does, but I'm not satisfied it's worth the expense and
power drain, which is a real concern on long flights ... by the
current regs I do not have the option of leaving it turned off if I
have battery power.

2NO