I have the AA12s with the 420 in my Raven II. It's Robinson's choice for an audio panel when a second com radio is required, the stock panel does not have enough inputs. The aux input for your iPod is still in the same location behind the collective with the AA12s.
There are other options for audio panels with more features, like built in cell phone interface. The PS Engineering PMA8000B is an example:
http://www.ps-engineering.com/pma8000b.shtml
Mike