I'd be willing to bet his core disagreement is light arrows and by saying 125 grain head he reduces this problem. Just a guess.

I hunted Idaho in 2002 with my wife, we had trouble getting her arrows up to 400 gr, had to switch to aluminum arrows to get it there and still spine right.

The move with carbons has been for lighter arrows for speed. My opinion is that KE is the totally wrong measurement for penetration with an arrow, you need momentum which is based on weight more than speed. KE works for bullets, not arrows.

Chances are your arrow will fly fine with 125 gr heads. Also chances are there is something behind the outfitters stance, probably related to carbon arrows and weight if you dug deep enough.

Hit them right and you will get good penetration, trouble comes on larger animals when you hit ribs, thicker hide, shoulder bones/shoulder blades. I've never hunted bear, so I have no clue as to their internal makeup. For elk, I had no issue with the ID 400gr rule, big critters!

--Bob