If my transom could take the power, I'd have one!
As said before, unless you do a lot of idle pottering, you won't notice the difference in fuel consumption between 2 & 4 stroke. 2- strokes also a lot lighter for a given horsepower, so that just leaves your view on emissions to sway you! However you then need to worry about the most environmetally friendly way of disposing of however many litres of used oil every service........
If it's in budget, you could do a lot worse than one of them.