I have XM, as it came with my Chevy when I bought it. I couldn;t justify spending money on radio until I heard Hair Nation & Boneyard ... I had been dreaming of a radio station that played music I liked, without having to change the channel every 2 minutes, & without the damn commercials. I was sold.
I don't think you can lose one way or the other. I have Sirius on my Dish Network subscription, & XM in the truck. I was more partial to XM, but now that they merged, they're both pretty much the same in my opinion. Depends on what your after.
For me, the 80's music is the same on either format.