On the back side, I have no problems as it's fairly natural. On the face side, the first 3/4" or so of the heel has to be sanded with the wheel rotating into the edge. That's very dangerous and you have to be extra careful unless you like getting hurt or even worse, damaging your razor
John, flap wheels are good for cleaning up major rust and minor pitting of your blades. It's much faster than hand-sanding and the 400 grit will give you a rough satin finish, that's passable. I left some of my blades like that, and I finished others by hand in higher grits (600-2000). Hand sanding is for the true perfectionist, even though Dremel finishes also look great (take a look at Jason's work). It really depends on your equipment, patience and expectations. I don't have the patience to spend 10-20 hours hand-sanding a blade lol.