If you are losing hate to a WHM, then it's the whm's fault. You can only do so much enmity generation when they spam medica II, when it's not necessary to do so pre phase 5. Even if they still have to, they need to be using Shroud of Saints more often. Full mp or not.

And FYI, I am a career whm. I pulled hate one time on Titan (my first run) and never did it again. You just have to watch it. People underestimate the power Medica I has too. I use it instead of II pre-heart. That's what your second healer is for regardless if it's a sch or whm.