Not sure it was mentioned but most places the truck only delivers 87. The drivers puts additives in the "premium" tank and then fills it with regular 87. The mid grade tank is usually just a mixture of premium and regular. If you are absolutely dead set on running E-free premium you could get the same results by adding something like Torco accelerator or Lucas octane booster. However, like everyone else has already stated it's kind of unnecessary for a work saw. I'm a 87 regular 10% ethanol user. I burn it up fast enough that I dont worry about it after I pour the Schaeffer's in it.
Like others here have stated, while I use the e10 87 in my saws and 2stroke premix tools, I never let my premixed saw gas sit around more than 2 months. I typically will just buy a gallon of gas, and mix it up with oil. I've only once had a need to mix up more than a gallon of saw gas a couple of times in my life.