I look at fuel treatment as pretty cheap insurance against major engine problems in these days of unknown fuel quality. "Ethanol-free" gas is getting harder to find all the time, although I've seen it advertized at some marina's. You can't even be sure the 10% ethanol fuel is really 10% these days unless you test it yourself! I have always used Stabil fuel preservative for the last 10-15 years, even before ethanol came along, to guard against plugged jets and loss of octane over time. If you plug an idle jet, it'll just idle poorly, but if you plug a main jet, it can be fatal if you're running premix because that lean cylinder is also being starved for oil! The only time I don't use it is if I'm on a long cruise where I'll burn up a whole tank in a day or two. They count on the ethanol to add about 3 points more octane to the fuel. You can have serious problems if you get enough water in the tank through condensation to combine with all the ethanol (called phase separation), because if you started with 87 octane gas, you'll end up with 84 octane if water takes out all the ethanol!
The resulting detonation can wreck an engine pretty quick! There are no valves to rattle in a 2-stroke, so the first obvious sign of detonation can be when it breaks a ring or blows a hole in a piston! If you want to be safe, buy 92-93 octane gas so that you still have enough octane even if you get some phase separation.