Sirius Catching Up To XM

I wish that both channels would merge -- XM has baseball and that weekly Bob Dylan show while Sirius has just about everything else I'm interested in. Their competition shouldn't be each other but hi-def radio, local radio, iPods plugging into cars, etc. There's simply no need for two satellite radio companies. But XM should be worried. Sirius is keeping up the momentum begun by Howard Stern. XM used to have almost double the subscribers. Now it's missing its goals and slowing down while Sirius is speeding up. Yes, it'll take some time for Sirius (with 4.7 mil) to catch up to XM's 6.89 mil. But with Sirius adding 600,000 and XM slightly less than 400,000, it won't take that long.