I think they got the cartridge idea from men stacking two blades in their DE. I'm not recommending it, though. There is something about the thicker SE blades that gives them more capacity, apparently; I'm only a spectator, like you, as far as that goes.I want something that really cleans my face in one pass--like my current Gillette.
What I've discovered recently is how one can generate cutting power from skin tension and more active angle selection, rather than fixed geometry. No hair is too tough for this approach. Not all razors allow low angle shaving, but some really, really cheap ones do!