I raid with Blacklisted. We usually have 10-12 healers.
http://realmplayers.com/CharacterViewer.aspx?realm=NRB&player=LaurelianaThere's usually 2-3 druids and the rest are a pretty even mix of paladins and priests. So there is hardly ever any point in competing with the paladins with speed and if I tried, I'd probably waste a lot of my mana with Flash Heals without improving my efficient heal much or at all. So I stick with Heal R1 and R4 mostly, saving Greater Heal for tank healing at hard-hitting bosses. I'm certainly not topping healing meters but I don't need to drink often and I have plenty of mana at hand if things suddenly go south, and it's not like our raiders are dying left and right due to lack of healing.
Obviously if a raid is lacking paladins, then Flash Heal becomes more useful because you have to keep healing up and I do use it occasionally, often combined with PWS if somebody pulls aggro and gets pummeled. But I don't just see the point of competing with Flash of Light (1.5s) and Holy Light (2.5s).