In the 1911 world, aluminum frame stuff is normally carried while steel is shot a lot.
I am not say you can't, but have you considered why the .40 is on a steel frame and not aluminum? Today's techniques with metals are great, but is there a chance that SA tried the same thing and decided on steel?
If I were manufacturing a 9mm originally and wanted to increase the caliber size, I would try what I have on hand first (aluminum), and if that did not work, then other materials.
The other thing is physics. The more mass there is, the more energy is needed to move it.
Steel frames have more mass and will absorb recoil better.
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Former President of the ECPT (Eifel Combat Pistol Team)