IMO there isn't any room for error regardless of caliber, so I lung shoot all my animals since I can always hit them there, no less perfect shots. I've tried bigger calibers and smaller calibers and have seen pretty much the same reaction from moose, at least with rifles as large as I am willing to go. They either stand around and let you shoot them, usually no matter how much you shoot them it doesn't much speed up the process when this happens, or they run off and you find them dead within 40 yards. At some point I went back to being a one gun hunter and I shoot everything with a .270 these days. The distance this bull covered after being shot was less than 20 yards, from what I've seen this is pretty good performance regardless of caliber. It happened to be in the wrong direction, but if you hunt near water you need to be willing to get wet, my main misgiving with this moose was having to get within arms length of him minuets after he fell.
IMO the best gun to shoot big animals is the one you shoot the most, the best gun to shoot small animals is the one you shoot the most, the best gun to hunt bush with is the one you shoot the most, and the best gun to hunt long range is also the one you shoot the most. For a long time this has been LSS Ruger MkII in .270win, we've got a great track record and I have no plans of changing any time soon.