I went through that same scenerio last year, was blown away w/Yamaha and E-Tec prices. I had 2 Merc dealers quote me 16k for 225 optis and ended up with a 225 Honda for the same price
I was quoted for the Optis. I had what Honda called a non-current engine, big deal, still had a full 5 year nondeclinng warranty. I put the engine on my 1989 23WA and mounted up 2 holes and went with the Power Tech 4 blade prop for mid-range efficiency. I get almost 5 gallon per hour at 3600 rpm, others here say that is wrong, but that is what my Northstar fuel flows shows. Even if it off 10% or so, still great performances for a 225 hp engine.