I did not use 9mm when making the high pressure comparison, used 38 special and 44 special which are lower pressure cartridges.
I said that I believe the 9mm is a very good round for short barrels, I never said that 9mm is a lower pressure cartridge.
Yes pressure is not the only thing that is of consequence when figuring ballistics, case capacity is a large factor in that the pressure builds differently and acts differently in a case with more capacity than is needed for the propellant charge.
Check out the ballistics by the inch for the comparable brand and weight cartridge, you will see that 357 mag really shines in longer barrels, with a 2 inch barrel velocities are much closer. 9mm seems to me to be a more efficient cartridge which is shown on BBTI by the 9mm actually starting to slow in 18 inch barrels, while the 357 mag is still accelerating.