well yea I guess it does matter if a madman killer has a high-capacity mag or not. the delay in shooting due to reloading is the time wasted on not killing more innocent people.... which is good!
As you said.... a simple revoler can kill between 5-6 people at one time.... while .40 Glock can kill between 13-17 people at one time.... but does this mean I support a ban on high-capacity mag? or ban on assault weapons? nope. as you said again - it is still dangerous in the hands of a madman regardless of type of weapons used in massacre.
fortunately enough... a massacre like this is still rare.