I've installed one on my Fairchild 24, and it was a pretty easy install. Not SkyBeacon or TailBeacon easy, but not hard either. The only real difficulty for us tube and fabric guys is dealing with the ground plane / mounting requirements of the GPS antenna. You need an altitude encoder that has serial output, so unless you have a newish transponder and encoder, expect to buy a new encoder. I have the GDL-82 combined with a GTX320 transponder and TransCal SSD120 encoder, and it took 2 days for me to do the wire up and then another day for my IA and I to do the paperwork and test flight. Has about 100 hours in service with no complaints from the FAA.
I can kind of see why shops don't like the GDL-82; it's significantly more work to install than the SkyBeacon, requires the customer buy auxiliary hardware like the new encoder (likely), and such. But I think it is a much better setup than the SkyBeacon/TailBeacon in the long run.