40 is a great round, it has a tendancy to recoil different than 45, I don't care for it as a range gun, but carry one for stopping power. It hits just as hard as a 45. Just makes a smaller hole to start with, the wound cahnnel may be euqal depending on ammo.
I prefer 45's but my shield has 8 rounds and it's smaller thinner tan my xds, and has a safety, for my dogs and grandkids who enjot jumping on me. I am used to Glocks. I can shoot a 9 or a 45 more accuratelly than a 40, but at distances under 50 feet it doesn't present a problem.
I shoot 9 the cleanest, but unless I have an open shot I am not dropping a guy with 1 or even 2 rounds. I am lazy and 2 rounds of 40 or 45 will usually do the job, if i hit a chest, or spine, shot.
Each to their own, it can go on all day, but just ask yourself which you would care to be shot with.
Handguns are feeble unles you shoot well. Large calibers pull and small calibers require 4 rounds, pick your poison, My ratio is 3 to 1 in favor of 45's, that's after 43 years of carry.
Also 45's are freking accurate, you can underload a 45 to 185 or 200 grain and stll make a big fraking hole. Two rounds and it's a really big hole. $0 is almost as good if you practice with it. 9 is surgical if you are a shooter. Get a glock 34 0r 35 0r 17llong slide in 9 and you have a 9mm with velocity of a carbine. It's just a big ass gun.
Almost like shooting a 22.