Hyho!
As a reader of this forum since a long time, I got many thoughts, hints and tricks for my tankadin-career until now.
I've had an eye on the AD-leapfroggin-discussion a while, I searched for other opinions, I discussed a lot with some highend-tankadins from the european-forum and
....finally I tried to build up an excel-sheet which show me the
best-case-scenario for AD to work and when AD will save tankadins life.
Best case is, correct me, if I'm wrong:
- you take one (or more) hit/spell/special/what ever, which bring you exactly(or as near as possible) one point below the AD-border (35% health)
- so you will get the maximum of "hp-range" AD can affect
My assumptions for this calculation:
- every hit causes the exactly same amount of damage (I know periodicaly dmg don't kill tanks in most cases, but easier to calculate with)
- my tankadin in this example get exactly 40.000 HP (I think with gear-scaling in Ulduar, no problem to reach)
- so AD will work between 1 and 13.999 HP, a pretty nice HP-range (remember: best-case!)
The Question my spreadsheet should answer:
Is there an amount of damage which will kill me without and let my survive with AD? (Ok, easy answer, yes

no need for a spreadsheet)
Give me a range of damaging-attacks, relativly to the max-HP the tank have, which let an tankadin with maxed AD survive an additional hit!
Here you have an overview of the relevant hit-ranges:
for explanation: I cutted off the two-shots(50% or higher), you will agree with me, two-shots doesn't affect AD at all
[img=http://img9.imageshack.us/img9/4608/adornotad.th.jpg]My conclusion:
- "Soft-Hitter", which will hit for "only" 25% of your HP (or less), are irrelevant for Maintanks and AD, so not worth to discuss about.
- the only dmg-range which
COULD be dangerous
without AD is at a point ~1/3 of your HP
Note: could be dangerous
I wouldn't call a boss which is hitting for ~14-15K (after all mitgation) as a real "Hard-Hitter" (take a look at the hitranges for Ulduar)
This best-case-scenario for AD only works when you have to take
three hits in a row, without any heal between.
I can't remember or build up an situation(maybe someone of you could?) where your healer aren't able to heal vor 4-6sec (including HoTs) AND the boss is hitting as hard as bevor in this time.
My knowledges of Encounter-Design from Blizz is:
- very heavy attack(Satharion breath, Gluth decimate, etc.) -> short break (for healer time to bring up the tank) -> standard attacks
- heavy attacks which will two-shot the tank -> no gameplay forced breaks for the healers
- normal attacks which can be healed through without big problems and healer-movement or something else
As an result for me:
In 3.1 AD isn't worth the three points you need to spend. I will take other talents instead...
For me 3% more inc-healing in EVERY situation > ~1-3% dmg-reduction in only very very special situations for example.
AD is
not a must have, of course there are some special situations it could save the raid, but to expensive for 3 points!
3 Points for a trash-tank-talent? Cut off the leapfrogging-effect Blizz, they don't know how? Look at WotN and get an idea!
Hope somebody will read this to the end

Any mistakes in my thoughts? Let me know!
Any mistakes in my post? I know! Don't worry about my grammar/words

CU
Cavalorn