My only bitch with the M9 was the trigger. I used to cheat a lot by cocking the creepy SOB during qual. Got caught a few times and pissed off others by holding up the firing line for a de-cock. One range tool made us all wait while my spit thumbprint aimpoint on the target dried. Didn't matter, I could see where it was and continued normal to usual "baseball" hole at 25 because my pistol craft is exemplary. If it's not a 1911 then it should be DAO IMHO. The M9 is otherwise accurate and durable. I do find the Glock superior and hope the military adopts it. I also hope they re-establish the .45 as it's uniquely American and puts a large American hole in undesirable humans.
Agree the stock triggers are rough, we got pretty spoiled as Marine armorers could make those things like a jewell for matches.
I didn't know anything about the p320 so I had to google it and read some info on them.... now I want one.
My main complaints on the M9 is the weight and the trigger. The trigger is fine once you get used to it but the Air Force doesn't get enough hands on to let most people master it. Usually the people who do well with the M9 fire pistols on their off time. And as far as weight goes there is no reason that a 9mm that only can carry 15 rounds should be that large and heavy.
I have mixed feelings about the M9 from having to teach others how to shoot it. It does its job and is accurate and reliable but I feel there is better out there. Its hard to find a pistol that will fit well with everyone. Due to the long reach and trigger weight some small handed people have to use two fingers to fire on double action. Not ideal but it works and I have only seen it a couple times. Even the Glock is a love or hate pistol depending if you like the grip angle or not. As far as the bore axis height that is shooter preference that is easily overcome for the average shooter. I can see it come into play for more advanced shooters but I don't think it is much of an issue.