I've shot a few, all with a 338, sometimes with two shots. I've helped pack out a bunch more, and i can't ever recall a moose hunt where getting the animal out wasn't the primary challenge of the trip. So i guess I'd err on the side of knock down power.
I killed my WY moose with my .270 shooting 140gr Interlocks. First shot was through the heart, second shot ended up in the face (I know I know) as he turned. He went right over on his back and did the bicycle pedal with his feet. I think just like any other game shot placement and bullet selection are more important than caliber. That said, if I draw another moose tag I will be packing my 9.3x62. Seems about perfect for moose.