Well, I somehow still have XM in my car. I may have it for life?! Just for fun I decided to plug in my old Sirius receiver into my AUX imput to see if there is that much of a difference in SQ. It was not a perfect test since the Sirius was being run through my old Clarion Calypso receiver, but both were being run through the BOSE HU into the same speakers. I would give factory XM 3/10 and the Sirius plugged into the AUX input 5-6/10. Although both are still terrible due to the BOSE system, the Sirius is markedly better. I now can swap back and forth and actually hear the difference.
After hearing the difference, I decided to do a full install using some DIY guides from this site.
The receiver fits perfectly in the cubby. Not a mm more in the clearance department. I didn't even have to use screws. It just fits snuggly.