Actually, when they were separate entities, XM was far "deeper" than Sirius, largely because Lee Abrams was in charge and, I guess, trying to make up for what he'd done to free-form radio -- obliterate it -- with his AOR Superstars format. But Abrams had some really wacky ideas, including using announcers with heavy foreign accents for IDs and liners just because he thought their accents were cool. I was sad to see some songs depart the playlists of my favorite channels after he left, but I'm something of a music geek at heart, albeit one who has grasped the psychology and reality that drive commercial radio's tight playlists.
As for music research, I listen to SXM's contemporary country channel, The Highway, fairly often, and get regular surveys to respond to. These surveys are done in much the way song testing is done by "real" radio. You are fed brief snatches of a few dozen songs -- with no indication of artist or title -- and are asked to rate them as love/like/OK/dislike/hate as well as tired of/somewhat tired of/not tired of. They're all songs that are already being played on the channel, some for months, others for only a week or two. I'm not sure how much impact these polls have on the playlist, especially since The Highway has long had an agenda of breaking new acts before mainstream country radio starts playing them, but at least some form of research is being done.
