You cannot solve edges with just <M, E, S>, beause the four edges in the M slice will stay in the M slice. The same is true for the E and S slices.Ah, okay. Thanks.
What about we solve all edges( top cross and bottom cross, or maybe alg subset of M, E, and S moves) Then, we could solve with some a perms or something . Also, if you have some, post your own methods.
Edges first is considered worse than corners first, because in corners first, solving just edges is easier since slice moves don't mess up the corners.