I read the Crutchfield review and noticed that there is no XM satellite module for the unit.
Satellite Radio: This unit supports both XM and Sirius Satellite Radio when used with the optional Satellite Radio tuner and adapter (sold separately. The KW-NX7000 supports the Sirius Connect Universal Vehicle tuner and JVC KS-SRA100 Sirius Satellite Radio interface (700SIRJVC1, sold separately). Currently there is no XM adapter available for this unit. You can also connect a Satellite Radio Plug-and-Play tuner to the unit's front-panel Auxiliary input.
You can buy the external and use the AUX INPUT, but its nice to have everything controlled by the head unit.
It will control a universal Terk XM tuner when using a Terk XMDJVC100 JVC interface. I guess JVC didn't want to license XM for some reason, so they interface with Terk. The manual for the KW-NX7000 even mentions the Terk XMDJVC100. It appears as though the JVC can fully control the Terk tuner using the XMDJVC100.
No JVC XM tuner exists, they all use the Terk XMDJVC100.