I hated mine on the glare shield. The instructions for the GDL 50 also warn of being in excessive heat. Mine was definitely hot on the glare shield. I mounted mine under the panel and use the connection to my 796 for the GPS. I had an extra transponder antenna under the plane that was originally used for a Monroe traffic alert box. I bought a transition cable from Amazon for like 15 bucks.
The ADSB reception is 10x better with the antenna.
If I were to do it again, I would buy the remote version. The GDL 50 has an automatic shut off but it seems that if it doesn't connect to something, it wont shut off.
So if you turn on your master for a short time and then off, it doesn't power off.
So when you go to fly, It is down to like 20% battery life.
So if I have to turn on my master for a short time without flying, I just make sure the GDL-50 connects to my bluetooth device.
Kind of a pain but not the end of the world. like I said, since this is the only plane I fly, if I was to do it again, I would buy the remote version