500k heal seems a bit off the top, my healer mate reaches rarely over 300k, just because there is not enough to heal against.
Take in to account that you shouldn't only stay and wait for someone to get damaged to heal him up, every healer class has damage abilites and should use them, thats what this medal system supports: "use everything you've got".
I am playing as a tank and I only get more thant 6+ medals when I try to do more damage besides my main "tanking pvp goals".
Sorry mate, but its just stupid, you do less then people who do damage and heal. And still you want the same rewards? And believe me more than 300k heal is just stupid, if he heals so much he is definetly ignoring some other goals in warzones, like objectives.