Tom, there was a comment by a coach on another thread about the Look pedal having more stability than the Speedplay. I don’t think so because most of the stability is in the shoe, its sole composition and how tight you strap it to your foot.
Since both the Look and Speedplay cleats use the same holes in the bottom of the shoe, this would not affect the stability. The only thing that would cause any type of torsional wobbling, imo, would be some sort of spacial tolerance between the peal and the cleat and that could happen to either of the pedal systems.
Hmmm. Good question. The answer is… Maybe. Now, a mechanical engineer could offer a more insightful perspective on this, but I’ll take a wack at it.
I was the National Tech Rep for Time Sports USA under Jean Pierre Pascal and Doug Knox. We set up pedals and shoes for the finest cyclists in the world as everyone wanted to be on Time pedals when they were introduced. I learned a lot there.
From a strictly non-scientific, observational perspective I think there is a lot of truth to what you are saying: That the shoe sole is really the “pedal platform” per se’. That is why we don;t mind selling $89 pedals but would rather a customer bought high quality shoes with a good sole and a very precise fit.
Now, with all that said, if we get a customer who has excessive “rolling” of their foot off the pedal as viewed from the front then that can sometimes be resolved with a wider pedal body pedal or the LeMond LeWedge or both.
I think a key component to getting the pedal/shoe interface optimally configured is minimizing the distance from the metatarsil to the center of the pedal axle. At Time we referred to this as reducing “rocking torque”, the sensation you have when you try to pedal hard on a tricycle equipped with those wooden pedal blocks when you were a kid.
FWIW, I am using the Time RXS Carbon pedal and am very, very pleased with it. I hope that answered your question.