Yes, a smaller bore will generate more stopping power per lb of force applied on the pedal. But, the tradeoff is more pedal travel to move the pads a given amount. The size of the wheel cylinders is what determines the amount of fluid needed to apply the brakes. Hydraulic 'leverage' is all about pounds per square inch, not just lbs or volume. Your pedal pressure spread over a larger piston results in lower PSI. I think you will be happy with an unboosted system. In the early days of disk brakes they were only found on sports cars and almost non were boosted.
