Rescue is an OGCD and can be weaved without affecting my healing. Typically, I just let DPS die to their own ineptitude though, because they gotta learn one way or the other. But if I need them alive, rescue is always better than healing them, because I need my healing for actual regular instances of damage and again, I'm not wasting GCDs on them. Moreover, I'm also not hardressing DPS, because again, they gotta learn.