For your article, it might be really informative if you took a couple of SA lines with different tapers and use them to illustrate these mind-numbing principles. For example, they make GPX with a 5′ front taper and Expert Distance with a 12′ front taper.
A graphic might color-code the line-speeds, say, from a 60′ cast as each part of the head reaches the front of the loop. Including a leader and fly might be cool for showing whether there are any differences in the tapers in accuracy of fly placement.
Just a wild guess, my guess it that the big difference might arise not at a constant distance, but if you compared, say 30′ to 60′ casts.
SA likely has something comparable internally, wonder if they’ll share.