Originally Posted by slayerfish
What are the advantages, if any?
Good question. The answer was easier a few years back when most outboards were smaller horsepower and 2 strokes. It wasn't that long ago that 300 HP was the most you could get in an outboard, and anything over about 115 HP was very expensive. Then the advantage was clearly with a sterndrive, where the lowest HP available was an 3.0 I4 with 130 HP, and you could get to 300 pretty easily (and relatively cheaply) with a 5.7 MAG.
Some things don't change as much. The way I see it, sterndrives are quieter than an outboard. Both at idle, and especially when they are running down the lake. They have longer strokes and a heavier fly wheel that allow them to develop more torque than an outboard. They run at a lower RPM. Parts may be easier to find and are less expensive. Service may be easier - you could have a car mechanic work on it should you need to. All sterndrives are 4 stroke - no messing with pre-mix or worrying about the oil injection pump going out, quiet, much less exhaust fumes.
Less important to fisherman, another advantage to a sterndrive is that if you are spending time in the water, the outdrive/motor is a bit less intrusive. Especially true for a boat with a swim platform on it.
To me, the biggest advantage to a outboard, especially true with fisherman who use the boat 3 (or 4) seasons, is that there is really nothing to do to winterize. Put it vertical, let the water drain out, and you are done.
I had a 350 Merc in a boat, and to winterize it, you had to pull 4 drain plugs on the engine. I could do it in less than 2 minutes, but it was an extra step. I have a friend with a 4.3, and he has told me there is one plug and some sort of a pump built in to quickly pump the water.
I'm not trying to convince anyone one way or another. Just trying hear other peoples opinions.