Marineland 150 Gallon XT 700 vs 1400 gph

I recently purchased a 150XT Marineland corner flow aquarium and found out that the system only supports 700 GPH to the sump. I'm currently working on this as a coral farm to build up some livestock. If I use both holes to the sump I could get 1400 GPH to the sump instead of 700 GPH. Would this make much difference or should I just use the kit for 700 GPH?

John