You really can't go over 1200gph regardless your drains can't handle it. So yeah I'd go smaller controllable and quieter.
Man you are really making me consider drilling it myself. couldn't i just drill it and put strainers on it and not worry about a weir? then i would have more room in the tank and I could bump it up to 1.5 or even 2" pipe. How necessary is a weir??