$3000 doesn't seem like much of an adder when you consider the peace of mind in knowing that you will never have a power problem. If the fuel economy is the issue you can prop the boat up slightly to improve your fuel consumption. I would definitely get the bigger engine for only $3000 difference.
"Tropic corridor, tropic treasure. What got us this far to this mild equator? We need someone, something new....something else to get us through" (James Douglas Morrison/The Doors)