RE: power output = gas vs. nitro
Let's go back to what you just replied. It depends on which class that you'd like to run in, either gas or nitro. You obviously know the other differences like fuel prices but you might want to look at what others in your area are racing if you're going the racing route. I'd still go with nitro for more speed, you'll find out that an OPS .90 will pump out those numbers but then you have an engine that will suck down the fuel. For you, it would have to come down to a matter of personal choice. With a nitro engine you are looking at not only the fuel but support equipment like a 24-volt starter, glow driver, etc.
Seeing how you're looking at the Aeromarine hulls, take a glimpse at the new Thunderbolt. Those that own them or have seen them run say that they are very impressed with them and one was another boat hull manufacturer!