From what I have read on the Yahoo finance board (XMSR) about their portable unit it has bad reception problems and dropouts. Likely due to the ground based repeaters. Sirius sats cover North America much better than XM's. What I would really like to see is a collaboration between Apple and Sirius so that I could access and download to my Ipod Sirius play lists. I am always hearing something on Sirius that I would like to record but can't find on I-Tunes. Rumors about something with Apple and Sirius abound. My idea would not be terribly expensive to implement and would make money for both companies and really grow the model.
An Apple Sirius collaberation would be outstanding. One of my favorite parts about Sirius is the title/artist feature. Problem is, half the time I can't find a pen and paper to write them down before I forget.
I'm buying an iPod if the rumors proove to be true.