The nice thing about the on dash receiver is you can move it from car to car.. I keep a docking station in each of my vehicles so I can move the receiver around. As far as which service, I have both at the moment and have been listening to both. Each service has it strong points, but I give the overall programming edge to Sirius. I listened intently last week to the discussion between Howard Stern and Mel Karmazin, current CEO of Sirius. Karmazin is slated to become CEO of the XM, Sirius merger if it's approved. According to the interview, when the services merge, we will get programming from both current services. It won't matter which service you subscribe to. Which channels stay and which ones go has yet to be determined. In my case, because XM is integrated into my Tahoe, I'll pick it up at the end of the year when my Sirius subscription expires. This is provided the services merge. If they don't, I'll stick with Sirius and the dashboard receiver.