RE: which one?
I'm another one who spent too many years around loud noises and suffer a ringing in the ear. I am a strong advocate of eye & hearing protection when on the range. When someone comes to my range, they wear eye and ear protection or they do not shoot or remain out there. People please for your own sake, protect your eyes and ears.
When out in the woods hunting, I only shoot once or twice maybe, and just let it fly without hearing protection. As for the difference between the two calibers, without a doubt get the .50 caliber. There is really no advantage of the .45 caliber in the distances you are talking. The .50 caliber will shoot as deadly out to 200 yards as the .45 caliber. Also there is be no advantage in the recoil or sound between the two. I just like the .50 caliber much more then others..