You guys do just the opposite of what I do. I shut down my powerheads and sump when I feed. I guess I probably don't really have to with the Formula One pellets as the fish get those fairly quickly.
But when feeding the blender mush, I have found that the clown and coral beauty will not touch the smaller pieces. They really want the big chunks. If I were to leave on the pumps, it would be a totally mess inside the tank. At least with the pumps off, I can scoop out the uneaten larger pieces of the mush.