[Afry]

It's all an opinion but you make some good points. There is no doubt that a properly setup duoprop IO can get some decent MPG but that is not the only factor. IO's still usually have the motor box to fish around and granted many parts can be resonable but salty bilge water and electrical parts don't mix well. You will have more through hull openings with IO's and still have raw water pumps and belts to maintain.

The new OB's (I like E-tec) are simple to run and very cost effective including when resale time comes around. Plus you can tilt the motor out of the water when slipped.