OK. Vanderpool should know what he is talking about however, if I have understood what is said correctly, there is a massive fly in the ointment. He claims that velocity is needed. The current 9mm service ammo is subsonic and about the same velocity as the 40cal, so given bullets of the same construction the 40 should still be better.

As I said early if you use +P ammo in a polymer frame pistol it tends to torque twist up to the right and takes longer to bring back onto target than the 40. So what have I missed.