I'm not well versed in the world of satellite radio..so forgive my ignorance. As far as I can tell...XM has a true portable that works like an FM walkman that allows live listening while walking or (in my case) commuting. Sirius however has yet to release such a unit. I've only found an iPod like unit that will playback previously recorded programming..not actual live broacasts. I've heard it told that Sirius may not be able to release a "live" unit bacause they don't have nearly as many transmitters/repeaters to make a live broadcast reliably heard.Am I on track here...or just way off base? Does Sirius have plans to release a true "live" portable unit?