Your comments are a perfect analogy on the two stroke vs four stroke but don’t blame Mercury as Tohatsu builds the Four Strokes for them. As you said Four Strokes are extremely cold blooded. To meet California’s star rating the factory sets them real lean. Imagine them in a colder climate, a lot of my customers break the tamper proof plug and richen the low speed on the carb just to keep there sanity. Heavy, you bet, slow to plane, yep, which results in your fuel consumption analogy. It takes “X” number of units of fuel to provide “Y” number of BTU’s to make “Z” number of H.P. Giving that it takes H.P. to plane the dinghy and to over come the weight increase and the performance decrease the throttle has to maintain a higher setting, hence, more fuel used. Give me a stinky two stoke any day.