As near as I can tell from looking at the numbers, the primary advantage of the MR props over the SF props is the difference in the APC Suggested RPM Limits or Safety Limits for MR and SF props.
The MR prop RPM limit is 105,000 RPM / dia. in Inches, the SF limit is 65,000 RPM / dia. in Inches. That gives the MR props some advantage in that they can be run with confidence at an RPM that is up to 40% higher than the SF props. And I say "with confidence" because the APC RPM limits appear to be conservative. They can be used up to their limits and even a little over without shedding blades.
The SF prop will do better on less power at lower RPM and then, as the RPM increases, the MR prop will come into the zone where it is better. So this is like arguing that apples are better than oranges.
The recommended RPM limits on the 10" and 12" APC SF props in the comparison testing summary charts posted above would 6,500 and 5,416 RPM. The MR 10" and 12" props would be good up to 10,500 and 8,750 by the maker's recommendations.
When the SF props do appear to be holding their or with or even outperforming the MR props on thrust, it is when they are being used beyond their recommended limits. Not a good idea at all.
The thrust from a prop comes with the RPM. And the input power required to attain a specific RPM will be fairly constant. Any motor that is fairly well matched to the prop as far as the Kv and battery voltage, and that can handle the input power without overheating, will give you about the same thrust with a given prop. So using one specific motor and trying to compare the performance 10" and 12" props and slow fly and non-slow props is going to have some combos that are not as well matched as others and some points in the RPM range where one cannot do as well as the other.
And then how you fly the props will change things again. You can't really expect to take a motor and prop combo that works well for a lower energy type of flying (photo, FPV, etc.) and expect it to do as well in higher energy types of flying.
