My only gripe as a tank when a WHM is spamming Holy... is when they don't heal at all and tell me that I should constantly be popping CDs so they can just AoE all the time. If you can differentiate between when it's time to DPS and when it's time to heal, that's fine, but it's just as annoying to make me do all the work to keep myself alive just so a healer can kill the mobs.