First of all, I wanted to say that is one of the most well-written, informative and organized posts I have read on Bikeforums. So thanks for taking the time.
I've used 2-bolt cleats since they first came out. Before that, I briefly had 3-bolt Shimano copies of Look. I naively thought the 2-bolt were simply an alternative design; for many years I did not realized they were designed for mountain biking. I have no recollection of what the 3-bolt ones felt like. You have inspired me to give it another try at some point.