Not sure if I know the answers, but it might help to know what your goal is here? The Super picks up perhaps a couple hundred feet per second compared to the 9mm, but the ammo is considerably more expensive and harder to come by. You can achieve most of that by shooting the wrath-of-God CorBon 9mm rounds; they are +P rated, but my Speer loading manual is saying the same of the Super.
There is a difference in max overall of 0.112", which is either a lot or a little,depending. Having examined the 9mm mags for my Defender, it looks like there is a spacer that might account for that much difference.
Curious to see what you find out.