Repower
Larry,
I too repowered my 1999 208 Adventure from an Optimax 200 2-stroke to a Verado 150 4-stroke. You might think that there would be many negatives to doing this. First, the engine weights are essentially the same, so weight was not an issue.
Second, there is no problem with getting the boat on plane although the Optimax was very powerful and would throw passengers to the back of the boat if I was not careful with the throttle. Now with less power, getting on plane is smoother and certainly much quieter. The tone of the engine sound is more pleasing as well.
Third, going from a 6 cylinder 2-stroke to a 4 cylinder 4-stroke, I notice some vibration in the 800-1000 rpm range. I am told this is characteristic of 4 cylinder vs. 6 cylinder engines. I've noticed it in cars as well. After 2 years with the engine, I don't pay much attention to it.
Fourth, the boat is a little slower at WOT (42 vs. 38 mph) and at cruise (25-27 vs. 22-24 mph). The best fuel economy (at cruise) is in the 3.8 to 4.0 mpg range.
Overall, the performance of the engine is much smoother (throttle is less sensitive) perhaps because of a better balance between the horsepower, torque, and boat weight. If you are not a "cowboy", you should be pleased with the engine.