I dont think your stupid or misinformed, and your car obviously is in good shape to survive for 200K miles. It just dosent make sense to degrade performance, and have knocking and pinging, just to save a few dollars here and there. I'd rather put the good stuff in my tank and know that I can run my car hard, have maximum engine performance without any possible ill effects.
You should dyno your car sometime, with your preferred 87 octane, and see what kind of numbers it puts out and how much pinging there is under load. It would be interesting for comparison sake especially sice you claim to maintain it very well.
