Rule 1: Don't use ellipses instead of proper punctuation.
Rule 4: You're bashing Sun_Tzu for playing the numbers game. But you're just playing the feelings game. We respect someone who provides numbers to show where results come from more than someone who cites feelings about what makes them happy.
Rule 6: Continuing that thought, provide evidence or your conclusions aren't helpful. You claim that mastery is better than haste at preventing a death with TW-GHW. Prove it. You're proud of your 45% mastery providing 27% more healing to a target at 50% health. Now prove whether that's giving you more healing than the equivalent amount of haste rating.
Originally Posted by Sun_Tzu
I concluded that the average value is half of the supposed value if your healing a person from 0% to 100%. That's not what you'll be doing most of the time, since a lot of emphasis in current hard modes is on topping people off. Mastery might, under these assumptions, perform slightly better when healing people up after big aoe, but unless it performs the task so much faster that had it been done with haste instead of mastery it would have been too late, then there really isn't any additional value to it.
On the other hand, being quickly able to respond to light random damage in order to keep people topped off, is more likely to save lives. And at this point, haste out-performs mastery.
And more to the point, when other healers jump in with larger heals, and the comparison switches to HR or CH, they will diminish the benefits of mastery a lot quicker, pushing the average further down. The average is only half of the supposed amount if you are the sole healer.
I've gone back and forth on the Haste vs Mastery issue and still haven't decided what works best for me. That said I have a couple of issues with your assumptions.
1) In the case where someone is dangerously low (let's say sub 15%) Mastery is more helpful in getting them out of the danger zone than Haste as long as TW is up (which it should be most of the time). Point for Point a Hasted GHW under TW will be superior in that situation if you had geared for Mastery over Haste.
I think using your example diminishing Mastery as you heal your target to full is a bit of statistical trickery. The most important heal in your example is the first one to land. In that case Mastery would be better since it brings the target well out of the danger zone. The following heals are meant to safely top him off which can usually be accomplished via our efficient tools (HW under TW, ELW and RT plus HoT)
You make the usual theorycrafting error of breaking things down to pure numbers without analyzing when and where those numbers are put into play. Yes over a long fight there will be many times where our Mastery sees half or less of it's effect and that's the main reason I haven't decided fully one way or another on the debate. On the other hand the reason I still give Mastery it's due is it's the best stat in the game right now to help save lives when they're most in need.....namely when they're about to die.
2) The idea that I would prefer Haste to faster top people off who are above 50% seems wrong and sounds like theorycrafting based on ICC fights. While the "triage" concept hasn't been as fully implemented as Ghostcrawler may have described it still exists to a degree on most fights. There is usually ample time to allow things like HST and our HoT's to "top people off" who are in no danger at the moment while we use our expensive heals on the deeply wounded in the Raid.
TBH the situation you describe seems more about looking good on the meters than actually playing smart. Tonight I tried mastery and bumped myself up to 45%. Even on players at 50% health that's a nice 27% boost on all my direct heals. Healing Wave under Tidal Waves actually becomes a very nice heal for the most part. When a Raider would stand in the fire and get dangerously close it was comforting to know that I had the best heal in the game at that point..... GHW under TW.
Right now I'm leaning towards Mastery in 25's and Haste in 10's.