Only problem with the portable sat radios is that you have to download and pre-record the shows. They do not offer "live" broadcast.
The SIRIUS STILETTO is a live broadcast radio. I have one. You can also record up to 100 hours of content to play later.
I do use my SIRIUS STILETTO on one of my motorcycles and it works ok.
You must mount it in a location that has a clear view of the sky.
If you run in on Batteries they only last 4 hours. and the slim battery only last about two.
You can use a car dock but you must use a external antenna.
The Stiletto has just enough volume to run one set of helmet speakers. 40 ohm speakers work best, any thing else there is not enough volume to cover wind noise.
You also need a good helmet with the least amount of wind noise. I use Arai helemts.
I have a Sirius Inv mounted on my Buell Ulysses. The Antenna is mounted on the tail trunk.
The Sirius Inv and the old Starmate ST1 are the only two Sirius radios that have enough volume to drive helmet speakers. any other Sirius radios need a external amp to have enough volume.
I've tried many different models to find the best audio for my riding.
I also use an iPod. The 1gb Shuffles can hold up to 240 songs and last about 12 hours on battery.
The Helmet speakers I use are on the Riders Warehouse web site (Aerostich)
http://www.aerostich.com/catalog/US/Stereo...rs-p-16311.html