In my experiences, and having played a cleric myself for years, the best clerics can use several different styles of healing, depending on the situation, and react quickly to changing situations. Drop a HoT on the puller, keep up a steady CH chain on the MT if his AC and HP permit it, but be able to duck out of the CH and, say, throw a quick heal on the chanter and a couple blast heals on the MT if an add comes in... Stuff like that. CH can be a valuable tool; it's mana efficiency is unparallelled, but it's not for every situation and shouldn't be your only trick.
Example time - pally I mentioned earlier was tanking a Creator for my zerker alt, some other guildies, and a random cleric we picked up. Puller pulls 4 on accident, the chanter gets them all nicely locked down... but the cleric was only using CH and it couldn't land fast enough, so by the time they were locked down the pally was dead (and 12k/2100 is way overkill for a tank for a Creator). I stepped up to tank; my zerker's not in good gear at all, and only buffs up to 8k/1200ish. Tanking one mob, not seeing any heals inc... Get down to 30%, then pop Reckless (equivalent to warrior Furious), so that should give the cleric 12 seconds to heal me up. No, I see a "CH inc" message just as I hit the floor. That's a case where CH doesn't fit the situation.
