Escaping should not carry a permanent penalty. At no point the player should be encouraged to reload rather than run away; I'd even say that (invisible) experience should tick per HP subtracted from the target to make running away and preparing for the repeat encounter more appealing on an emotional level.
(Exhausting a certain quantity of a finite resource is a permanent penalty. I wasn't keeping track of development so far but I sure hope enemies are infinite. Breeding mobs in D1 was fun but not particularly immersive.)
