I've decided against going the Sync route. I'd have to downgrade to the Shaker 500 head unit and by the time you add up the cost of the radio, Sync unit and installation you're looking at $1,600. Not worth it for a non-touch screen system, IMO.
The Z110BT is being phased out. You can still find it and the price is right (~ $900) but I've been looking at the new models. The upgraded feature sets and interfaces are much nicer, IMHO.
Right now I'm looking at 2 specific units, the AVIC-Z120BT (successor to the Z110BT), and the AVH-P4200DVD. The Z120BT is a full featured touch screen nav unit with bluetooth and media connectivity (DVD, SD, iPhone, USB). Very nice system, but pricey. The P4200DVD is a Multimedia A/V receiver only (DVD, SD, iPhone, USB), no nav or bluetooth. You can add both capabilities by buying add on units though.
Z120BT: Great interface, does everything you could ask for, incl. voice commands. Expensive, but if you absolutely have to have nav functionality, I think this is the way to go. $1,400.
P4200DVD: Amazingly nice interface. Fully customizable and easy to use. It'll even display album art when an iPod/iPhone is connected as the source. $495.
5 Part Review
Parking Brake Bypass
iPhone Control Demo
If you need bluetooth connectivity, you can buy the CD-BTB200 unit which connects to the head unit and provides hands-free calling and bluetooth audio streaming. $179.
Bluetooth audio streaming:
You can add nav to the P4200DVD with the AVIC-U220, but the price is $400 and the functionality is not as nice as the nav head units.
Summary: If you absolutely NEED nav, get a full up nav head unit. Otherwise, look at one of the Multimedia A/V receivers and add a bluetooth unit. At this point, I'm looking at $1,400 vs. $675 and trying to decide if I really NEED nav and voice commands.
What do you think? I'm open to any thoughts, criticism and advice.