I understand and respect your advisor's line of reasoning. However, the problem with "gain-loading" any firearm is that under life-threatening stress, most people quickly lose count of how many rounds they've fired. In that situation, they won't know what's coming out of the muzzle next.
Since I for one want to know what's going to emerge from the muzzle on each pull of the trigger, I keep my guns loaded with the same ammo from top to bottom. Different rounds in the shotgun's butt cuff, or the pistol's magazine, are more forgiving in this regard. They give the mind a "break-point" during the reloading process to remember that as soon as the new loads go into the gun, something new is going to be coming out of the business end.