you got it right. i run an older model avh-3100 and nuvi in my Z, and avh4100 + droid4 in my G. AVH's are a nice system, reliable too.
only down side was back then BT was an option and the BT module had issues pairing with motorola phones for some reason. this is why i use BT off the nuvi (ecoRoute guages + speaker phone) + recently got a auto on/off Motorola roaster2 for my G.
if i was to get a new HU today, i would get the AVH4400BH for my Z.
im still not a fan of having to have to pay $95 or watever for map updates. for maps i will use nuvi/droid4 until these stereo manufacturers offer free map updates.