My guess is the outboard does better at slower speeds. You may know that the nature of pumps is that there isn't a neutral. So, having less power is an advantage at slower speeds/neutral.

I don't think either has much an advantage at speed other than more hp is better when you turn and that edge goes to the inboard, generally speaking.

Other things to consider, inboard pumps are more efficient per hp can have more hp, but they are heavier. Outboards don't have an engine box inside the boat. Outboards don't run as shallow and have more exposed parts. Being exposed can be advantage when you need to clean out your grating. Finally, there isn't a trim on inboards, so you may want to consider adding trim tabs if you buy an inboard.

I really like my inboard, but they make different types for a reason.