We've got 90-octane ethanol-free juice around here for ~10 cents more than premium and it goes in all the small engines with Sta-Bil, and I rarely don't drain fuel after use, with no issues thus far, though everything is stored in a humidity-controlled environment. I also run the same ethahol-free stuff in my Toyota as it consistently gets 10%-15% better fuel economy than the premium juice (ethanol-percentage math says this shouldn't be the case, but my fuel consumption numbers don't lie) . I feel bad blocking the diesel pumps at Sheetz, but the ethanol-free stuff is only at the diesel pumps and not the regular gas pumps for some reason.
Edit: I recently sold several of my old mowers (10-20 years old) and all three had minimal varnish in the carbs and fired up like new, even after sitting for a few years unused.