XM Radio for my '07

I want to replace my Sirius radio that is integrates with the MFD with the XM version that will also integrate w/ the MFD.

I can't seem to find WHICH unit I need though.

I've seen used versions of the Pioneer GEX-P920XM XM Satellite Tuner

http://www.amazon.com/dp/product/B0009I96LC?tag=priuschatcom-20

That claim to work w/ the Toyotas. But I wanted to check to see what you all thought.

Thanks in advance.

(For those of you asking why, I have a source at Sirius XM that has indicated to me that the XM is going to be the lead platform moving forward. In addition, in the area I live Sirius keeps cutting out which would be fixed my going w/ XM.