I spent many hours bow fishing from a small jon boat years ago. It was a lot of fun, as long as it was calm. Any noticable wind, say 5mph, completely changed that. It did get good fuel economy with a 15hp motor that would go a little over 20mph. I don't know about more modern motors, but I don't think any of the older ones would be able to get on plane at just 5hp, especially with any noticable amount of equipment. Not planing would be a major hit to fuel economy, so sometimes more can actually use less, lol!
When not being used for their intended purpose, a simple jon boat can make a good little roof when flipped upside down for covering things.