Well I have a '96 Yamaha 20 hp. It is a 2 stroke, and it runs great. And I do not have to mix oil and gas, as it is oil injected. My neighbor has a 4 stroke 15hp Yamaha. It weighs more than mine for sure. So it is definitely easier on the back. Still heavy though. Mine is about 104 lbs., if I recall. As far as trolling is concerned, I bought an electric for that. Personally, I don't worry that much about the gas mileage. I mean, I am going to head out and fish no matter what the price goes is.
Enjoy your new motor!!
Hey Mike! How much do you charge for a tuneup?