It still comes to power to weight ratio, one of the biggest advantages to max rated Hp is you have much better control of the boat when you need it out there. You can get the bow up faster in heavy seas, and when loaded with people etc. You should burn less fuel when running/crusing with a higher HP engine, you will be at a much lower part throttle crusing than with less HP using more throttle to get at a crusing speed. The correct prop is also required. As far a dual outboards, typically ( not always) you don't see dual outboards till you get to much larger boats than 23 ft, so it is not a true comparision. But this is all my view. I know when it's really rough out on the big lake, I want every advantage I can have to get back home. Generally 85% of the max recommended HP is the lowest alot boaters would accept.