The barrel test can show one thing and that is a fixed blade will always help you for those days that something happens in the field that would not have occured on the square range. Such as a twig hitting the arrow, buck fever making you snap the release instead of having a smooth release and so on and so on.
Again, in my opinion if you are going after a heavy animal you are better off with a fixed blade. All heads will kill a deer when properly placed and every head for the most part will kill the game if you happen to gut shoot it and give it time. But the fact is there is a great chance that if you hit bone the mech will give you and issue, while you can always depend on a good solid fixed head to break bone and get the job done, again for those days that someing happens in the filed that usaully does not happan on the square range.
Shoot Straight!