CR does reduce detonation margins. Detonation is not detectable by pilot and can cause catastrophic failure (hole in piston). It is avoided by rich mixture and reduced power.
Engines in combinations of displacement and CR never certified are experimental.
High compression and more power can mean different power pulses and harmonics in crank and prop... See above... experimental.
I have a stock (except for EI) O-360A1A with 8:5:1 CR. I have no intent of running Mogas but I could. Higher CR forget it (please).
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767