I have my 300xs 12 inches back on my 03 with both skid planner and hydrofoil on, no backwash. take the skid planer off and leave hydrofoil on it gets back wash. skid planer on ,hydrofoil off gets no back wash. so as I see it the skid planer is the main player in the back wash problem.
Now as far as hole shot,, they are both needed . my boat jumps out the water with both on , you take one away and the bow raises up on take off
Now I haven't moved my battery to the front , I only run 2 batteries , one in the back by the tank and one in the left wing as far forward as I can get it.. I run my motor , 1 inch above the pad ( yes one inch above) my boats ran 100 with a 4 blade hydromotive prop I think it was a 33 ,a better driver could get more out of it but that's all I wanted at that time lol good luck