A lot of people run Eheim 2028s or 2217s on 75gs, whose flow rate is less, like 200-250 gph...is there sometimes a differnece between companies though? like perhaps even though the rate is lower the effective biological filtration can be higher?
The only concern that I would have is if the tank was not drilled, then you'd have to deal with the overflow/weir issue. Not too fond removing water from your tank over-the-side. Only had a sump once on a non-drilled tank. Had one of those CPR overflows with the aqua-lifter pump.
Even with the pump, managed to overflow the thing about once every 6 months.
You don't have to worry about this with canisters.