I think it's all in the clip. The clip does not move, warp or bend. Also the way the clip is positioned on the reel makes it very easy to feel the edge of the film against the bar on the reel w/ your fingertips. This lets you know if you've got the film on straight or if it's crooked. On the generic reels I have, the clip is on the bottom of the bar, making it much more of a guess if you have the film lined up straight. I know that people are nuts about these reels, I guess i'm one of them now.
Anscojohn; I do agree about not using the clip on other SS reels. If you can learn on a hewes, you can probably load anything once you get the hang of it. I still can't load plastic though.