Ford's AudioPhile system

I know the hu is probably a POS, but i am looking at buying an 06 fusion. My question is...

is there a difference in the AudioPhile HU compared to the standard 6-disc changer on the SEL. The fusion has standard 6 speakers, and then there are two holes in the rear deck w/o the audiophile system, which are used in the audiophile system. Im curious, because, i will most likely replace the speakers, but not the HU as i would like to have the stock look and functionality of 6-disc and steering wheel controls. are there enoguh channels on the stock HU?

i think it would be nice to replace the the six speakers and add two extra in the rear,

you can tap into the stock headunit using a LOC .... I competed with the stock headunit in my accord for a year. But you need to replace the factory speakers and amp them.