Now that you have gone with XM, be sure and check out XMFan.com. It's a forum dealing with XM but they really deal more with the Roady, the SkyFI unit, and the XMPCR.

I went with XM because I had a Pioneer head unit that supported it. If I had a head unit that worked with Sirius, I probably would have gone that way. I like XM and listen to it constantly when in the car, but I have found some channels replay certain songs more than others, and it can get a little annoying. Other than that it is a blast!