Would 2 emperor 400's, and a fluval FX4 or it's equivelant bee overkill for a 75 gal. When I say overkill I don't mean logically I mean would it be bad for the fish? I gots to have my crystal clear water.
Not necessarily... you can set these things up with some forethought so the current isn't too bad. like one emp at either end, and the canister with a spraybar return to minimize current. I'm running 3000+gph on my 200, plus a 2000gph koralia 4 powerhead, and the current isn't strong except right beside the koralia.
I jsut got my first spray bar and they do wonders. I added an Eheim Pro II to my 120 and you can't tell any real difference in the current. The water does seem to be clearer.