I have used rear fill in a large vehicle just to help fill in some of the gap. I usually cross from 3500 down and use some form of attenuation on it. My preference is not to use it at all if I dont have too.
I have a friend that is nuckin futs about rear fill. He thinks you get surround sound with a stereo signal running all speakers. I got him a set of nice comps for his truck and cheap coax for the rear. He put the comps in the rear and the coax's in the front!? He thinks it is the shit. I asked him if he listens to his home or computer speakers turned away from them. His response was I like my sound that way. I want it comming from the back.
What a tard