I have used Opti-2 & mid-grade gas mixed @ 100:1 since 1983 and just can't understand why anyone would want to use any other ratio. Once one of my lawn maintenance crews mixed a batch of Opti-2 @ about 300:1 and called me to complain about equipment stopping instead of idling. I went to the job site and they had 8 pieces of 2 cycle equipment that would only run @ full throttle. One of the workers told me how he had mixed the fuel so we brought everything back to the shop, drained the fuel, replaced it with 100:1 and did not have any problems.
Use Opti-2 & mid-grade ethanol free gas mixed @ 100:1 and run the equipment @ full throttle. The harder you run it the better it will run. No one will ever go back to a richer mixture after running 100:1 for a few tanks.
We use this fuel/oil ratio as our shop fuel and it goes into hundreds of 2 and 4 cycle engines each year. We use truFuel in most of the new 2 cycle equipment we sell. If the customer is purchasing MotoMix with their new Stihl equipment we use that for start up.