Improved Divine Spirit by the numbers

Having just hit 70 on my priest this morning, my mind is on heal specs. I'll probably stay with my holy DPS spec for a little while for attunements and rep grinding and whatnot, but sooner or later I'm going to go healbot. I just know it. For my money, the big debate as far as healbot specs go right now is Improved Divine Spirit (IDS) -- that is, whether you'll be better off with 21/40/0 or 23/38/0 (builds are for illustration only; I haven't been able to figure out whether Holy Concentration is worth it or not). These builds differ by only two points: the first has no points in IDS and 5/5 Empowered Healing (EH), the second has 2/2 IDS and 3/5 EH.

Anyway, I was researching the issue, and eventually made my way over to the Priest forums, where theorycraft superstar Trepidation (aka Trep) crunched the numbers and came up with a very nice chart of how much more you'd get from EH vs. IDS for various heals and various values of +heal and spirit. EH always helps your Greater Heal and Flash Heal more than IDS does; the question is whether the boost IDS gives the rest of your group, as well as your other heals, gives it the edge. The charts are too long to repost here, but I encourage you to go check them out. However, for commonly-quoted early endgame values of +1000 heal and 500 spirit, here's the breakdown:
  • Rank 1 Gheal: 1.74%
  • Rank 7 Gheal: 1.10%
  • Rank 7 Flash: 1.17%
That is, EH will give you somewhere between 1–2% more than IDS will, for your Gheal and Flash. These numbers will go up as you get more +heal, and go down as you get more spirit. So does IDS help other casters in your group, and your other heals, by 2% or so? If so, it might make sense to get IDS. Otherwise, it seems that EH is a stronger choice.

What has your experience been? Have any of you had a chance to test some pure healing priest builds yet? Another question I've been wondering about, as I alluded to above, is Holy Concentration. I like it in theory, but I'm having trouble freeing up three points for it. How has it been working out for you, if anyone has it?

This article was originally published on WoW Insider.