I looked into the Yanmar 2GM. Wouldn't even consider the 1 -- partly because the 2 has freshwater cooling and a saltwater jacket: longer lasting engine in salt water. I was also told that I wouldn't be able to tolerate the thumping and the low hp of the 1.
But, I too am sticking with the outboard.

Mike -- what's the verdict on 6 hp 4 cycle? Is it enough to power the boat through moderate current?