Sheesh, York has good solid info here. He reads and experiments and races and learns. Is not part of the cult of any one builder, listen to him.
If you really want to learn how to port, do one step at a time and see it it makes an improvement or not. Follow the scientific method they taught you in highschool. Take your stock cylinder exhaust, polish it, reassemble and try it. Faster? Now hog the hell out of it leaving it rough. Faster? Now polish it. Faster? You have learned something. Even through failure you learn something.
If you just follow and video or book article and go a dozen different mods, what have you learned for sure? Nothing! Just gained some hand skills.
Ken is a smart and sharing man, well worth listening to. He is willing to share and to work for the folks who don't have the time to learn on their own. From reading York's writings over the years, I'd say he has done plenty of hands on too, and I don't hear him slagging anyone here.
Steve