I have it. My front stage is hertz and 280 watts today, I still like rear fill. Makes it louder and gives a better sense of space. But with a caveat: Running it on equal amp power to the fronts and paying top dollar for real high end rear fill like alot of people do on here is a waste for SQ applications, and NEVER use power for it if the front stage needs more wattage. Mine runs off head unit power and the fader is still 1/3rd to the front. The imaging is there and yet it seems to bring the soundstage closer to me. But if I bias anything any further than this towards the rear sounds start coming from speakers, not from the windshield.
Example: It's a little retarded to me when people go out and buy a cheap 45x4amp, awesome front comps that need 130 watts, and rear fill coaxials, then send each of those four channels to one speaker and starve those fronts of power despite peoples' recommendations to the contrary.
Then when they show up after awhile and wonder why things aren't loud enough and detailed enough in the front stage and its suggested that they bridge the amp some of them still protest that they want to keep the rear stage amplified although they usually can't even explain why it's important to them.