1. ADS-B Out does not require a transponder if you use UAT, which may offer more economical options as we get closer to 2020.

2. What about making yourself more visible to other GA aircraft? Pilots who have not flown in ADS-B equipped aircraft have no idea how much traffic is out there that you don't see. People way over estimate how well visual scanning works. I often can see other GA aircraft on ADS-B within a mile of my position, and even though I know exactly where to look, I still can't see the aircraft visually.