I've got a 912is in my S7 and have over 400 hours running Chevron 92 Octane with Marine formula Stabil ethanol additive and no problems. The engines run ethanol fuel in snowmobiles all the time with no problems. I replace the plugs and change the oil every 100hrs and the plugs never look bad. I have a transfer tank in my truck with a filter on it, and when I change the fine filter at 100hrs I cut and inspect it. Never any debris. The gas has stained the fuel sight gauges slightly, but not enough to make them unusable. They will be replace in 200 hours with all the hoses. On the road I use 100LL with Decalin, but it is a very small percentage of my consumption. The only difference I notice is the lead on the plugs.
Bob