I would have to agree with the possibility of defective equipment/poor installation for the post(s) about bad reception. I have a factory service manual but I have never looked at the wiring schematics or components for the factory installed systems. I have had Sirius installed in my Ford Ranger since the first week of July 2002. I installed all the equipment myself. Kenwood dash unit, satellite receiver, and Sirius brand (or branded) antenna. With my setup, if the signal drops, it says "Waiting" or "Acquiring Signal". If it were a chronic problem with the equipment, I would look at the satellite receiver box connections, or any problems with the wiring from the antenna to the receiver/decoder box. In the almost 4 years that I have had it, I rarely experience loss of reception. It has probably been in excess of three to four weeks that I can remember losing the signal. I can however, vouch for the compression and sound quality issues. Especially with higher frequencies (cymbals etc. ) and live music were the music drops out and you are left with silence. Well almost total silence. It almost sounds like the hiss of a tape without the Dolby noise reduction turned on. I also think the sound quality issues may be amplified if a premium audio system or aftermarket equipment is used. I have only heard XM on cheasy stock speakers, not high end systems, where recording clarity can make or break music. I am all for whatever makes you happy. I personally prefer the programming and reception of Sirius and the sound quality of XM.
BTW. My friend has a XM equipped 'Burban. I have experienced more dropouts in his vehicle than mine. A coworker has a Isuzu, I mean GMC Duramax, and his XM reception seems to be fine.