Depends what the purpose of your sump is for, if it's just to move water between the top and bottom then why have a sump? For a manifold or return jets? use a closed loop
If you have a skimmer or other filtration there, then in all honesty a slow rate sump is perfectly fine, it gives the skimmer time to clean up more water so the water going back is more likely to be cleaned. All sorts of other filtration, carbon, phos*(cleaner), etc use slow flow rates anyways, so why waste energy with an over powered pump.
And I concur with the use of a 1.5" drain, it's 2.25x the size of a 1" drain, plus that means less water per volume touching the sides (ie places where viscosity slows things down).