Yes I have XM. I have a convertible, so roof mount was out. I placed the antenna in a little "corner" on the dash to the left of the steering wheel. It is not very noticeable there and gets good reception. It was also fairly easy to run the antenna wire underneath the instrument panel (a little black tape to make sure it stays out of view.) [attachmentid=17082]
I have a Roady2 which broadcasts to FM and works fine. I plug it into the lighter and the wires run under the plastic covering between the passenger and driver foot space. Didn't need any tools, and it works great. [attachmentid=17083]
Also, if you change the display color to orange it blends well with the orange instrumentation in your BMW. :wink I've also found that the remote is useful for changing channels without having to lean forward.
I'm pretty pleased with this setup - if anyone has a better solution please post.
I've included two attachments with pics.