I think he meant, he doesn't drop the mag and top if off after chambering, or at least that's how I read it.
I carry +1.
Ya know - You are right... I had to re-read the post.
Going back to the OP - So, it should be the same as down-loading mag by one with one in the chamber. I prefer to have N+1, but I can understand if someone just carries N with one in the chamber. I've always been taught that after one chambers a round (in a perfect world) one should load a fresh fully loaded magazine rather than pop out the mag and load one more round into the mag. This is for reliability. Not everyone has an extra mag sitting around fully loaded, however.