My limited experience with 2-stroke oils is in 2-stroke dirt bike engines, but it has been an interesting experience. I generally run whatever "quality" oil is priced right or I can get my hands on. This ranges from $6 a quart Yamalube 2-R to $16.95 a quart Bel-Ray HC-1. With an average lifespan for a piston of around 20 hours, it's pretty easy to see any accelerated or reduced wear.
My conclusion so far is that I have seen no difference in wear no matter what oil I run except when I blow a crankshaft seal and start sucking crankcase oil.
What I have seen are differences in cleanliness of the engine. A major part of 2-stroke motorcycle maintenance is cleaning the exhaust valves. My particular bike is notorious for fouling exhaust valves. After running some of the brands of synthetic oils, my exhaust valves come out cleaner than they go in. Of course, outboards don't have any such thing but keeping the ring grooves clean is important to maintaining proper ring seal. My observations so far have been that the synthetic blends do carbon up some in the ring grooves, on the piston crown, on the exhaust valves, and on the combustion chamber. Redline synthetic does leave deposits on the piston crown, none in the combustion chamber, minimal in the ring grooves, and some on the exhaust valves. Bel-Ray HC-1 leaves some in the combustion chamber, minimal on the crown, none on the exhaust valves, and minimal in the ring grooves. Amsoil Dominator performs very similarly to Redline. Amsoil Interceptor is the interesting one. Everything in the cylinder is absolutely spotless after the pistons entire lifetime of 20 hours. I think the last engine we pulled apart had one fleck of carbon under the spark plug. It's also one of the cheaper oils at $10.95 a quart.
I've also noticed that if you overheat the crown, you'll get carbon build-up on that hot spot regardless of what oil you burn.
Basically, if you have a boroscope available, you should use it to determine what oil keeps your engine the cleanest and run that oil. Don't worry about brand, they all seem to do fine at wear protection.