Don't take this wrong, you do what you do and I'm ok with that, I'm big on freedom whether I like something or not.
I've killed literally over 1000 whitetails in my life, used to shoot crop damage in Va. for three years which accounts for 90%+ of them. All on crop damage went into a reefer field dressed and driven to butcher for food bank. Out of those, I've killed nearly 100 with subsonic projectiles suppressed, only 3 were with an air rifle. Keep shooting them with a pellet and no pass through, and you will be lucky if you get 3 or 4 before you have one run full bore and gone, no blood trail and you will not find it unless you are extremely skilled, lucky, or have a well trained deer tracking dog. They most certainly do run hard sometimes when hit with subsonic and extremely quite weapon. The distance they can travel if absolutely dead as soon as hit can be astonishing. Worse one in my life, I recovered it, ran well over 200 yards as the crow flies with no heart. Biggest piece of heart when I dressed him was the size of my thumb. No heart pumping, technically dead at the shot. No heart, blood trail gone in way less than 50 yards. Until oxygen depravation from no blood circulation shut the brain down, it kept running, crashed at full speed when that happened. At full speed that distance was covered in no more than 18 seconds, probably less.
Don't get me started on head shots. The time it takes from the point of no return pulling the trigger, until a subsonic projectile even travels 25 yards is an eternity for the head to move hopefully for a complete miss. Don't think a deer can move a lot in that time? The one deer I never recovered, I shot at around 40-45 yards, 2,200 + FPS muzzle velocity. As the sear was breaking, I watched helplessly as the calm feeding deer whirled at hyper speed and was blinded by the muzzle flash in my scope. First thing I picked up with my eyes after the muzzle flash was a coyote leaving the area, perfect timing him spooking that deer as the sear was breaking. There was a mess where the deer was when I shot, actual strips and pieces of meat all in the blackberry briers. Not much in the way of blood so I walked back to camp to give it time before tracking. Back at camp was the reason I never recovered that deer. State trooper that hunted with us was sitting there talking to his friend who was a game warden. I talked to them a bit, told them I was waiting to track the deer for an hour or so. They never left, and in my state they would consider it night hunting if I went back in the woods armed to track a deer, so I ended up going in un-armed. I bumped the deer nearly an hour after starting to track him, he stood up no more than 15 yards from me. I would have put him down for good if I had a handgun on me. Two of his legs on the side he had to me, were non-function pegs he just swung like crutches balancing on his two good legs on the off side. He slowly moved away and I backed off until morning. Bullet had entered rear ham never getting deep and splitting the hide spewing chunks of meat, got stuck under the hide travelling full length of rib cage, and then took out a bunch of front shoulder before exiting, from lack of blood and color of what there was, no arteries were hit. That deer was full on broadside when the sear was letting off. From sunrise the next day till nearly noon I looked for any kind of sign/blood/anything with no luck.
My personal rule on subsonic hunting, shoot something that cuts on entry a big hole and exits, nothing but ribs and lungs. Feel free to do as you wish, your choice.
