I have Sirius radio in four vehicles, and am going to install it on my red SEEG (which according to the dealer arrives tomorrow). According to articles I read before signing up for Sirius, XM was the first and is the largest provider and is also less expensive than Sirius but supposedly Sirius has more satellites, and better coverage. Also they have no commercials on the music channels, and is $12.95 a month as opposed to XM being $9.95 a month. After the first one you activate with Sirius. each additional unit you activate cost $6.95 a month. I know I have been pleased with Sirius and have had no reception problems. I plan on putting the antenna under the fairing also and will let you know if it works or not as soon as I get it installed. I have not had XM so I cannot compare content or verify that Sirius does have better coverage. I just went on articles I read from various sources, including Crutchfield, when I bought.