I’m not sure about the cougar and leopard comparison. North American hunters seem to think cougar is easier to kill than a black bear so... anyway i think most people would rather deal with a black bear than a leopard.
My thinking on this has been heavily influenced by an article reprint posted in this discussion on handguns for bear and cougar:
look for a long post by JJHACK, title “Hunting bears with handguns”
He has a section on police wanting to take treed bears with their duty guns, and the relative performance of the different calibers.
Now a bear is not soft skinned like a cougar (cougar with carhartt coat?) but the author makes a comparison between a 300 pound treed bear full of adrenaline and a 300 pound criminal hopped up on dope.
I’m not sure how exact the comparison between a 300 pound treed bear and a 300 pound male wearing heavy clothing and hopped up on dope. But I think it is worth thinking about.
Now, I train for what I am most likely to meet. While it's possible I can bump into an escaped lion or Cape buffalo, chances are anything that goes bump in the night will be two legged (belonging to Al Shabaab). Chances also are if I shoot the bad guy several times center mass with good quality HPs, that he'll probably decide to go meet his virgins. Additionally, and this is important, I am very good with the 9mm, i am IDPA ranked as a sharpshooter (and I am sure with more practice I can go to Expert), and I love the capacity of the 9mm in a Glock. Also important, if my mate has, say, a 1911 with 7 rounds of .45, and I shoot the terrorist center mass several times with my 9mm Glock and NOTHING happens, then I can assure you my mate with his .45 1911 will also get the same reaction: nothing. We will know we are shooting at a zombie (or a terrorist with body armor), and opt for another approach.
Bottom line is this - with modern HP ammo, the caliber wars are dead (and the 9mm won). While there is a place for other calibers, and there are many who are deadly accurate and fast with bigger calipers (including 10mm and .45s), for most the 9mm is the perfect equation of penetration, expansion, controllability, capacity and cost! That is hard to beat.