I think that the radical evolution in fly casting in the latest years has come, mainly, from two sources:
The availability of affordable high speed video equipment and the possibility of discussing technical issues with some casting geeks from all over the world… and in real-time.
The discussing part has been overdone. The learning experience that motion-freezing provides is still alive and kicking. The more I work with slo-mo the more I love it. Even a still camera with high speed capabilities can surprise you.
One of the milestones in the never ending road to casting improvement is when you discover that what you think you are doing is very different from what you are really doing.
Recently I spent two weeks of trout and grayling fishing with a good friend. Once in a while I like to put the rod aside and take the camera, specially when the fishing is as slow as in that particular afternoon. I shot a couple of series of stills at around 4 frames per second while he was fishing the water. Nothing related to casting technicalities, I just liked the light and the misty background.
When taking a look to the results I immediately remembered a statement from a recent conversation:
“I like to wait for the tug of the line in the backcast before starting the forward cast.”
So if some improvement could be derived from just getting a piece of new gear I think that, at this point in history, it is better to browse camera catalogs instead of fly rod ones.