My 2c, stick to the owners manual's recommendation. My answer would be different if I had a vintage engine.
IMHO, 91 octane with ethanol or 91 octane without ethanol is still 91 octane. Either/or is fine with me.
However, I do avoid ethanol gas for winterization. Ethanol is hydrophilic — it likes to absorb water thus corrosive.
The larger question is do supplemental fuel additives have any value? They are sold in all kinds of formulations, yet their use is neither standard practice or specifically advised by manufacturers.
Engine gurus often add all kinds of things to oil and gas.
The subjective findings in that thread regarding engine idle "feeling" etc is not too compelling, but the findings about mileage changes, and the findings about qualitative improvements in reduced engine oil consumption and teardown condition of the engine make me want to try it out.
My dual sport consumes oil which is pretty normal for the type of engine, and I run it WOT 75% of the time. If I can reduce that consumption by keeping the ring pack seal more efficient through a cleaner burn, then I have an excellent outcome.
I will be testing out the 2 stroke oil addition to the fuel and gauging any changes in engine oil consumption over time and spark plug condition over time.
The changes will have to be significant or the laws of diminishing returns will apply.
Interesting stuff.