9k is about right on what it'll hit on all your Hime against a non-Dark. Double HP would probably get you to like 9500ish like me, so everyone damaged would still die. In addition, double HP would gimp your damage output a lot, wouldn't it? That makes it more likely for Rage Overdrive to happen, no?

... unless it gimps your damage output so bad that you don't get to Rage in time, but I doubt it.