So after reading the manual online for the AVH-X8500BHS and determining what I need:

CD-IU202S for the iPhone 4S

HDMI/USB to Lighting Cable into the Apple Digital AV Adapter for the iPhone 5

I was wondering if anybody here has done this before? My wife has an iPhone 5 and I have the iPhone4S and want to be able to interchange phones/functionality with AppRadio in the AVH-X8500BHS when either of us are driving the car alone.

But what happens when both the iPhone 5 and 4S are plugged in at once? Will I run into some kind of conflict and need to just have only 1 phone plugged in at once? It'd be nice to be able to charge both phones at the same time.

Hmmmm, getting a little concerned here after rereading the manual. The diagram in the manual shows both the CD-IU202S and the Lightning cable going into USB1. AppRadio should still work regardless if the iPhones is plugged into USB2 right?

AppRadio should work on USB1, adding a second phone or Ipod to USB2 will give you access to it's stored music but the other stuff like appradio and pandora is not going to work through USB2

AppRadio should work on USB1, adding a second phone or Ipod to USB2 will give you access to it's stored music but the other stuff like appradio and pandora is not going to work through USB2

Ouch... I reread the manual again last night regarding AppRadio and looks like you are correct that AppRadio must be set up through USB1. This sucks since we can't upgrade the 2nd iPhone to a 5 until the end of this year.