If that mag change makes a difference on one then it also has the same difference on the other.
Okay, I thought it over, and I believe this may be a call back to the School Shooting vs Self Defense examples, earlier.
"Same difference" for one. Okay, one is a lone shooter, ASSAULTING a public place. So, mag changes is significant, because he's set out, from the outset to maximize casualties.
The other is DEFENDING yourself. Right? Correct me if I'm wrong, and this isn't in response to the 10 round magazine debate.
In a Self Defense Scenario, your priority shouldn't be maximizing casualties, or firing rounds as quickly, and indescriminately as possible into a crowd. It should be defending yourself, and nothing more. If you can't do that with 10 rounds of let's say .40 caliber (Since it was designed specifically for the 10 round Glock magazine) then you're probably already dead.
You can "What if" all you want, but you're at a disadvantage in a Duel, when one guy knows he's in a fight before the other. As the number of attackers go up, your chances of getting more rounds drop, exponentially on the Defense.
On offense, say assaulting unarmed schoolchildren, you might have to worry about reloading. On the defense, 6 rounds was enough for Elmer Keith, and 10 for the FBI, under the expert recommendation of Jeff Cooper., to perform the duties of Law Enforcement, and 8 rounds (In the 1911) was enough for the Army, for decades.
More rounds won't save your life, either You will, or you won't. It's not a magic talisman, nor security blanket. It's what You need to save Your life. If you can't do it with 10, you can't do it with 30.