Have a SL2 unit which i enjoy greatly. Have a family member with Xm account and am thinking about getting him a XMp3 unit. I don't know anything about XM units and need some information. Is this unit similar to the SL2 in that if you want to use it for a base unit at home one would need to purchase the seperate home docking unit? i would imagine he would want to use it as both a portable unit but also run it through a home stereo or radio for home listening. Any input appreciated.