There is no reason why you should ever be putting the slide forward on an empty magazine. If you're reloading, you will be putting a full mag in the gun. If you're unloading, the magazine should be out of the gun entirely. If you really need to put an empty mag in an empty gun, just put the mag back in after the slide is forward.
Different capacity magazines have different strength springs. When empty, one will push up on the slide stop harder than the other. When you're trying to drop the slide on an empty mag, you're fighting that spring pressure. But as long as the magazine seats properly, feeds properly, and locks the slide open after the last shot, this is a complete non-issue.
0331: "Accuracy by volume."