With DPS, more is almost always better. If you crit, yay! More DPS! If you proc something YAY! More Spellpower! Which leads to more DPS!
But we healers, we’re a different breed. We grumble about trinkets with procs. We rabble about crits (eh some of us anyway). We moan mightily about random effects. More is not necessarily better.
Why? Because groups live and die by predictability, not random chance or by sheer volume (except when you heinously overgear the content).
Sure, the random crit does save a person now and again where a normal heal might not have… but most “saves” come from a healer’s ability to quickly estimate how much healing is needed and how much a given spell will predictably deliver. You can’t hit a small heal and hope it crits. You have to hit a big heal, and if it crits, it may well be overheal. And if I proc Divine Aegis… it could be on a target who needs it… or it could not. Again, can’t rely on it.
Bigger is not always better if you are slow. In terms of heals-per-second, spellpower may give you the most bang for your buck. But if you are assigned to heal multiple targets, quickly whipping off many small heals may be what is needed, even if your “raw numbers” are lower. If you need to heal 4 people, and #4 dies because you can’t get to him fast enough, it doesn’t matter how big your heals were on #1, #2, and #3. There are some interesting discussions that the ICC buff is providing so much spellpower, that it leads to mostly overheal, and you’d be better off in some cases stacking other stats.
Faster is not always better if you are capped. Heroism doesn’t do a hell of a lot for a tree’s hots, because I’m already haste capped at a 1 second GCD. I will be able to throw out the same number of hots, though with the glyph of rapid rejuv, I do get faster ticks. I tend to switch to tossing regrowth during a heroism phase, because that spell benefits the most from the haste boost.
I said “this target” dammit! Smart heals are all well and good, but I would still like to control whom my heals hit. Sure, you’d think that the lowest health person is the one who should get the heal… but sometimes that’s not what you want. Maybe the person with the lowest health is in no immediate danger. Maybe I want my aoe Hots to splash to the tanks who are currently topped off because I know they WILL be taking damage. If you have the 4 piece tier-10 bonus,instead of waiting to see if the hot jumps there on its own, and you’d just end up overwriting the hot if it does jump.
Is this going to change in Cataclysm? Perhaps. It will be less about “getting there in time” and more about managing the big picture. Keeping people at lower health throughout the fight means that crits will seldom be overheal.
With mana being a scant resource, however, control will be more important in other respects. Healers will need to watch closely to make sure that aoe heals are hitting the maximum number of targets, so that they are not wasted.1 Discipline priests will have to shield only targets which are likely to be damaged enough to consume the shield, and avoid pre-shielding too many people “just in case.” I bet we’re all gonna know how much our shields hit for!2 Shields may be “too strong” to be used on anyone but tanks, because only on the main tank is the shield guaranteed to be consumed. Trees will probably do less pre-hotting so as not to waste hots on targets not taking any damage. The lost art of pre-casting and then cancelling may be making a comeback (I’m rusty on that).
And of course, we’re going to have to relearn to stick to Healing Assignments and communicate amongst ourselves to control where the heals are going, so we don’t waste mana overwriting each others’ stuff. Oh noes! Healing renaissance incoming?