Guess I'll put in my 2 cents worth..... I've started shooting suppressed weapons in '66 while in the Army. Guess you could say I "hunted" with them back in a land far away back then also. I started using a 30 cal suppresser a few years later for sport hunting. I used it with the .308W, 30-30, 30 Carbine, 223 Rem and 22LR. I mostly used the 311041 HP and the 311299HP in the 308W and 30-30. In the 30 Carbine the 311316HP were cast of very soft alloy, mostly 30-1 or 20-1 GC'd and lubed with Javelina. Ran at 1050 - 1100 fps they remained about as quiet as a 22 cal pellet rifle.
I found them to be effective on deer and vermin when the ranges were kept close, usually sub 100 yards and mostly less than 50 yards. As already discussed, bullet placement was paramount. Hunting/shooting from a fixed position/stand/hide was also essential. I learned early on that "still" hunting was not a good idea because one cannot precisely place the shot on moving game, even at close range, precisely enough with the low power sub-sonic loads.
I've also hunted deer and vermin with full powered jacketed loads with the same cartridges. Whether or not the animal shot heard the ballistic crack was a moot point. If multiple shots at multiple animals were to be had I never found the ballistic crack to actually spook them off. It is the boom of the muzzle blast that does, and that boom is eliminated with a proper suppresser. Most often it confuses the other animals as they don't understand what it is or really realize where it came from. I've marked a deer's ear only to have them run into each other at the 'crack". It is almost impossible to get a direction the shot came from when only the "crack" is heard. I've had coyote run at me confused, just stand there or run over to the shot one to see what was wrong with it. Sometimes they'll jump and trot a few steps, but they stop to look around. Shot over the back of one at 600 yards and he started a sneak on the bullet impact.
I also learned over the years that larger caliber bullets at the same sub-sonic velocities always killed a bit quicker. Seems a large hole going in trumps the same size hole going out...... Thus, I built a 45 ACP on a M98 Mauser action using a Rhineland conversion. I run a GC'd 245 gr 230 gr 452490HP cast of 30-1 at 1050 fps out of it. It is deadly to say the least.