I am considering getting a Z2, but what are the navigation issues I read about with the Z2? The D3 is tempting because of all the good reviews of the iPod and Bluetooth interfaces but the lack of a second CD/DVD drive is a serious drawback. 2nd disc drive aside, what do I gain by going with the Z2 over the D3?

Bigger screen, voice recognition, no nav disks, 10 gigs of music storage, more navigation views, dual zone, blah blah blah.

The routing issues are on all Pioneer's, not just one particular model

Another question: Are the wiring harnesses interchangeable between the D2 and Z2? It would be really convenient if I could just unplug my D2 and plug in the Z2. Thanks

No. Shouldn't take you more than a couple minutes though