iPhone, Bluetooth & Sirius App

I am disappointed to hear that so many are complaining about the sound quality of XM satelite. I am currently a Sirius subscriber (have been for years) and to be able to listen to the stations I want to I'd have to fork over an additional $4 a month for the "Best of Sirius" package on any XM subscription I'd buy. However, I now use the free app from Sirius to listen to all of Sirius on my iPhone...and was wondering if anyone with a GIII uses their iPhone to connect via bluetooth to the system to listen to Sirius in such a manner? Is it necessary to even connect via Bluetooth, or can you actually just stream your iPhone through the iPhone hard link? And how well does the iPhone stay connected to 3G when on the road?

I'm expecting to take delivery on my Barcelona Red Prius IV today or within the week- HOPEFULLY today- so I don't know what to expect.