Roy,
Full weather data is around $59/month; they also offer a subset of the wx data for $25 or so a month. I probably wouldn't subscribe to any wx here in So. AZ, except for the fact that I work for the company that provides the lightning data that XM uses.
The 396 has a separate menu page for the radio. The only downside is if your passenger wants to channel-surf.
You can't display the GPS map and the XM information at the same time...
John
