I have never been a big fan of the 9MM in the first place. Not in the military or police service. I especially have never liked the Beretta pistol. I'd choose the SIG-SAUER, HK, Glock or Colt in that order, anytime over the Beretta.
The problem with the 9MM is in the military, is one that can not use the cartridge that would make it capable, i. e. the better hollow point bullet, because of the GC. So, as long as one is stuck with a full metal jacket bullet that doesn't expand, etc. I'd rather stick with a larger harder hitting bullet.
As far as some soft body armor goes, the 9MM has a better chance of penetration than a .45. It depends on the number of layers in the vest and the length of the barrel of the firearm. Most .45's are easier to stop than 9MM.
A number of LE agencies switched from the .38 caliber 6 shot revolver to a high capacity 9MM; however, many now have gone to the .40 caliber or .45 caliber, because of lack of stopping power, etc. of the 9MM, even with the better ammo.
You'll see a lot of SWAT cops using the .45. Of course LE is able to choose from the great selection of hollow points ammo on the market now days, where the military can not. Of course, shot placement is still very important in the stopping power no matter what you're shooting!
Actually the new Sig 220 in .45 would make a great replacement for the Beretta, IMHO