I think marc's statement concerning ACAS/TCAS is one of the best
reasons to fly with a transponder, along with facilitating the
extended use of some wave windows. I fly along/in mountainous areas
that have alot of bizjet/heavy aircraft decending over them and
although I haven't had any close calls, I've seen traffic come out of
nearby clouds (not on airways) going fast enough that I'm happy I had
something to let them know where I am before there is any visual
contact! I used to have a Terra, but it wouldn't fit in the
panel(it was hung off the side-in the way of egress) and parts aren't
available. I got a microaire and it's been easy to use, has worked
great, and didn't cost two arms and a leg.
Will