A life of study and experience will make any man an expert in his field if he is dedicated. I have studied engines and engineering since day one, and spent a lifetime practicing what I studied. In the course of my own stupidities I wrecked more engines that most, just by pushing things beyond limits.
Low octane fuel in high performance engines will increase combustion pressure rise in time, and eventually cause knock and bearing damage. I found out in non graphite coated MVVS engines, that the compression ratio of these engines is right at the limit with our 95 octane gas (which is 90-91 US pump octane) If you run the engine well cooled, at light loads and high rpm, you may get away with it. You will however damage an engine by too low octane numbers. You will not damage the same engine by using too high octane. So if you want to use only one fuel mix, use the higher octane that MVVS requires. Fact: MVVS has a higher specific output than DA, which explains the higher requirements.