Personally I'd stick with a loupe, maybe 12-15x. The 20x ones start to get very small fields of view and require better lighting by comparison.
After spending a bunch of time on my work microscope, I'm not so sure I'd recommend the lower power microscopes for serious study of your edges. There is a world of difference between what can be seen at 200x and what can be seen at 400x, and again at 1000x. Digital enlargement adds nothing to the resolution. Maybe helpful to speculate, but not capable of showing the cutting edge in detail or depth of the cutting edge, both of which are necessary to get a good idea how an edge will perform based on an image and/or how your actions are truly effecting things. Would be helpful for cosmetics, macro features/defects, and overall technique.