Have a question for you Zumo owners with far more expertise than me. I am considering buying a Zumo 550. However, I currently have Sirius radio that I'm using in my car and 1800. Since Sirius and XM have merged, have any of you transferred your Sirius subscription to XM to use with the Zumo or do you know if it can be done? Also, I would ideally like to be able to listen to the GPS, radar, have the ability to make or receive a phone call, mp3 thru the headset or external speakers. What would I need to make this happen?