I also have Pocket Tunes Radio running and think it's a great stopgap and well worth the $10. But you can't compare a native app like the one the Nicemac team created to an application that is automating the navigation through the Sirius/XM web page. The native app had all the station switching and song ID info, along with lyrics and song purchasing.
As for the legality of the Pocket Tunes Radio app as it relates to Sirius/XM...who really knows. I thought I saw in the Nicemac twitter feed that Todd thought the approach was clever and probably within the SiriusXM rules. The Pocket Tunes Radio app is just navigating the web page and streaming the audio - just as if you were sitting in front of your computer and doing the same thing. It's really hard to argue that Pocket Tunes is doing something wrong.
So, in conclusion...really enjoying Pocket Tunes, but waiting for a great native app. I truly hope that Nicemac gets their payday because they got shafted.
--DotComCTO