Certainly helpful to me - the little blue graph makes it very clear why a reversal speed that is impossible to reach can give useful information, even if approximate information, at lower speeds. But then I always find graphic representations easier to grasp than... pretty much anything really. I suppose it does matter what is the shape of that curve.
I have to admit though, after reading all this, I am still not clear whether the Yak 1 wing should be stronger than the 109 F wing, for instance, or perhaps I should say be more resistant to certain types of damage and stress combinations. Having had my wings removed often enough while flying both types, I am fairly neutral about what happens in the game!