There will be a few opinions on this.
Some guys like to run bilge pumps in flatwater, or surf.
Some guys running flatwater (including myself) like to run a scupper along with dual 500 bilges. I plug my scupper tube from inside the engine compartment when riding surf.
Most surf guys that I know do NOT run scuppers and only bilge pumps. O'Side Crew in particular.
Personal opinion... I run an xmetal scupper with a piece of aluminum window screen clamped over the outlet tube in the engine compartment. The scupper is a one way valve, so why install another one? And the window screen keeps all zip ties, nuts, screws, bolts and any other foreign objects out of the scupper and preventing it from sealing. So for me, it's a simple, cheap and reliable set up.
Just my .02
Others will chime in with more opinions, so pick which one will work best for you.