Well I installed my HU with the Metra GMOS-100 and had an issue with not being able to adjust the volume using the radio buttons or the steering wheel controls and also had an "ATT" error message on the screen. I called Metra tech support and they were no help. The tech asked a few questions and said it sounds like it's a radio issue, and said to call Pioneer. Of course I called Pioneer and the tech said it was a Metra GMOS-100 issue.
I took the HU to my local CarToys dealership and had them bench test the HU and it worked fine. I then purchased the PAC OS-4 and SWI-RC, did the install and everything went smooth. I'll be returning the GMOS-100 for a refund on Monday.
So now the learning begins. So far I really like the unit. Pandora is working great using my Galaxy S3, my music is working without any issues using bluetooth. I converted a blu-ray movie to a DVD-5 and it played without a hitch. My SrriusXM is working using the DIC on the dashboard via AV2 and I'm very please with the way the navigation system is working. Now I just have to spend a little time with the manual and the forums to learn all I can about the unit.