More octane means a higher temperature needed to ignite it, that's why it's less likely to pre-ignite(detonate), but never heard of that downgrading performance. I AM NOT AN EXPERT, but my experience is that it's just a matter of safely running the least octane needed to save cost.
12:1 is pretty high, and the engine builders I know advise against mixing fuels (although you'll no doubt hear that a lot of people do it). You might be OK with avgas which is 100+ octane, and keep an eye on your plugs for signs of detonation. Otherwise stick with the 110 and not worry about it.