Trav,
I would seriously consider the .50 for a deer rifle. Components and supplies are everywhere and the ball is big enough to do the job reliably.
The .45 is a fine ball for target use, but I have helped people search for deer after using them and when we found the deer, I believe that a deer similarly hit with a .50 would not have traveled far at all.
My .45 barrel is in a closet as it was replaced by a .50 barrel long ago.
CS