The residual valves are only needed if the master cylinder is below the wheel cylinders, they keep the fluid from returning to the master cylinder.
Smaller bore equals less volume with more travel to reach X amount of pressure at each wheel, where as, the bigger bore equals more volume with less travel to meet the same X amount of pressure. With that said, you should have just as much braking force requiring slightly more force on the pedal with slightly less pedal travel.
Joe
