Pioneer heads and add-on units are excellent in maintaining standards. They've kept the IPbus system for a long time, meaning that a head from 2000 can plug right into an XM unit from 2005 or an iPod interface from right now, recognize and use it with just one single digital cable connector that can be daisy-chained. It's like USB, almost.
I like that. I just don't know that the current AVIC line is worth it, yet...both due to the cooling van noise I mentioned, and also because the graphics are still not up to par with what I expect for 2007, very blocky, somewhat clunky interface.
I'd wait for the next model. I can fit a double-DIN in mine, so I'd been eyeing it, but I wanna wait.
Also, check to see what the preouts are, on the some of the AVIC series, they were horribly weak voltage levels, which would lead to loss of signal in the run to an amp in the trunk.
Right now, I stilll have a DEH-P4000 head, IPbus-connected to a GEX-P910 XM reciver and CDB-20 analog input. The rest goes via Monster Cable back to the big Infinity amps in the trunk and the rest of the system.