Hhhmmmm, the 243? JK LolI vote for the heavy bullet.
Your scenario is a difficult one to put apply a visual to. If you choose a more extreme scenario, I think it is easier to imagine a difference.
If you are in a face off with a Hungry Griz at 50 yards, would you prefer a 243 Win loaded with an 85 gr Partition or a 358 Win loaded with a 225 gr Partition?
Great point, depending where you hunt you might not be the top of the food chain, better safe than sorry.