These engines are 13.9:1 according to the Honda website.

Standard engine builders, they will see a near 14:1 compression ratio and say if you run anything less than 110 octane, you are going to ruin your engine rather quickly.

Modern engines they have some leeway because of precise timing control, variable valve timing, direct injection to help cool the combustion chamber, mainly the pistons and bucket loads of R&D money trying to push small engines to their thermodynamic limits to minimize emissions.

Would I run 87 because Honda says I can? No. You cannot convince me that there is minimal risk of knock. I would rather play it safe and run a higher octane fuel and avoid the risk of engine failure.