I'm a Sirius subscriber, and I listen to the Underground Garage for the most part. Yes, I'll admit Little Steven throws in stuff that's not really "underground," but I still love the channel, because it's turned me onto a lot of stuff that I didn't know about before. I recently bought CDs by Syl Sylvain and the Rich Kids, and I plan on getting stuff from the Mummies and Vertebrats in the near future.
BTW, I happen to like that song by Kelly Osbourne, "Come Dig Me Out." LS said he discovered it by accident when one of his employees was playing it on his computer at work. No, it's not a "garage" song, but it's still a great song. Very punk like, at least.
As for playing Springsteen, well, lets face it, he does have a vested interest in promoting the new album. I'm not crazy about the new album, but I can live with it. There are a few older Springsteen songs that LS plays which do have a "garagey" sound, i.e. select tracks from "Darkness on the Edge of Town" and "The River."
I'd also like to point out that I'm glad LS throws some variety into the mix, because if he played nothing but "pure" garage rock, I would get bored with it.
As for sponsors, you really don't need them for satellite radio. You just have to convince Sirius or XM to give you your own channel. Sponsors are needed for syndicated shows on terrestrial radio.
As for the merger itself, I have mixed feelings on this. On one hand, it could help to keep satellite radio in business, but on the other hand, I'm worried that making it one company will jack up the subscription rates because of the lack of competition.