No offense taken, but here's my view.... My 1801 w/ 115 also has a top-end of about 38...providing the stars align (Clean hull, trimmed out, tail wind, following current, 1/2 tank of gas, 2 people onboard). This means I have to push 47K RPMS to maintain a cruising speed of 26 mph. I don't want to do that. I don't want to use 80% of an engine's power to maintain a cruising speed. It's not efficient and it's disconcerting to know there ain't much more in the throttle if I need it. So while I may rarely take an 1801 42mph...it would be nice to know that I could if the situation demanded it. It would be nicer still, to cruise at 66-70% engine capacity.
Additionally, I have experienced following seas wherein the 115 would not push through the trough. I think some of this may have to do with Parker intentionally (I confirmed this with them) mounting the motor higher than normal. A higher mount may help you in the skinny-water bays down east, but it doesn't help you get the bow up (if you have no tabs). So I'm gonna take my motor down a notch next month...which I anticipate will further diminish the 115's cruising performance.
Bottom line: The boat is rated for a 150 and that's what it needs.