If its a question of metagaming I usually don't allow it or call for a roll. For example: Fighter A just bought a brand new masterwork longsword. He encounters a Rust Monster and wants to simply run away to avoid losing his equipment. He can try to run past it (provoking) or jump down a small cliff, landing in a Bush of Burning Rashes and taking some damage. Metagame-wise the player knows that going over the cliff he will keep his sword, suffer some falling damage (definitely not lethal) and maybe pick up some ability penalties from the effects of the bushes. If he runs past the Rust Monster he might lose his sword, armor or some other expensive piece of equipment (but he probably won't take any actual damage). To my mind, if the player decides to jump off the cliff, he's probably metagaming. The decision isn't based on what his character would be thinking (i.e. "Ow that's really really going to hurt") it's based on what he as a player is thinking (i.e. "Equipment is expensive but healing damage is free."). I try to encourage my players to avoid that kind of thinking. At the very least I'd call for a Wisdom or Charisma check for the character to force himself to go over the cliff.