Bergo,
I have a 30hp Yamaha 2 stroke (the most basic version) on a 4.15m tinny. It is a SeaJay tinny with high sides and the motor pushes it and two blokes along beautifully.
It takes a couple of pulls to start when cold, then will start first pull all day. I can't speak highly enough of it as a motor, it has never let me down. I don't take much notice of fuel consumption as I have run around fishing all day and still had fuel left in the tank.
It runs Yamalube oil at 100-1 and you see barely any smoke at all.
I am no expert but for what it is worth, that is my recommendation.
Matt