You should have no problem using your healing skills. If you are having to heal enough that you are pulling hate from the tank then your tank is bad or your party isn't avoiding enough damage. You can always weigh your odds as well. If after a Geo or during stomps if you know you need to heal 2k damage but your Medica only does 1k then of course you would use cure 3 as it's double potency in a single GCD so you can get back to watching the tank. Can't just let people die cause you might pull hate.