Brian, I am more than happy to acknowledge your superior experience in these things, but I must admit I'm with Constabulary on this. The feet look the same type as those on my little 201K (domestic) and I'm blowed if I can see any advantage in filing out a notch like that. Plus, as you say they are two different type of feet, so to prove that cutting the notch makes a difference the comparison should be between two of the same feet, i.e. before and after.
Of course, I could be completely wrong......
I see you posted just as I did, Gymnast. Interesting tests, but as I said you should do the comparison between two of the same type of foot in order to get an accurate result.