The evinrude/ johnson guy was probably talking about the new e-tec which I have heard is pretty much bomb-proof. The first scheduled service for them is 3 years. Will have to wait and see though. They are supposed to use very little oil and are very light and compact. Only thing is that they really won't apply to you as their current range only goes up as far as 90. Unless you get twins that is. Would have got one if they made a 135.
Yes, you are right about the Optis and 4strokes. There is a thread about Optimax fuel economy here, but you basically forget about economy above 4500rpm.
Optimax fuel economy