This ignores the fact that the WAR is using IB on every burst damage rather than using it continually on CD. This is the major factor that allows a well played WAR to exceed the average expected performance. The value in a WAR isn't going to be in the average performance but in the fact that they will be able to, when properly played, have the equivalent of Rampart up for *every single* burst attack. The 6 second duration matters less than the 20 second CD, which means that you shouldn't treat IB as a traditional CD but rather a highly leveragable part of mean mitigation. Basically, you have to compared the ability to have 6 seconds of 20% DR on demand every 20 seconds with static 25% increased hp and 20% +healing to a flat 20% decrease in damage taken. A WAR only has to use Inner Beast once every 30 seconds in order to achieve the same mean mitigation over time.
This doesn't tell the whole story though.
While IB is active, assuming that PLD has a 5% non-buff mitigation advantage due to using a shield, PLD would take 95% of static mitigated damage and WAR would take 100% but would require only 87.7% of the healing that the PLD does to recover from it, which, for our purposes, is mean mitigation; for eHP, the WAR has 25% *more* than the PLD while IB is active. The WAR, using IB properly, takes *way* less total percent of max damage from the burst and requires a helluva lot less healing to recover. For time periods without IB active, WAR will have ~95% of the eHP that the PLD has and will require 109.65% of the healing that the PLD requires (because of that shield mitigation).
In the Twintania example (it's closer to a 6k mitigated burst on a PLD, btw, which is why surviving it pretty much *requires* an adloq/stoneskin, and the DPS is closer to 500 for the auto-attack portion since a single healer can maintain the tank outside of the burst recovery), where we have an intense burst damage event every 30 seconds that amounts to roughly 50% of total damage taken is within the 6 second IB window (6k baseline mitigated burst on a PLD with ~1000 mitigated damage per GCD for ~400 DPS on auto-attack portion; (6000 + 400 * 6) / (6000 + 400 * 30) = ~.47), which is the average expected use rate that the devs/time averaged performance of IB expects, you would end up with the WAR requiring 98.675% (.5 * .877 + .5 * 1.0965) of the total healing that a PLD requires. This is, of course, ignoring the new SP debuff which, if it's anywhere near 5%, will eliminate the PLD shield advantage completely and WAR will end up requiring 93.75% of the healing that a PLD does.
Put it all together and you get a WAR having a *monumental* advantage on both eHP and healing required on the burst damage phase and a negligible advantage/disadvantage that vacillates slightly based upon auto-attack damage for the remainder of the time, which isn't really a major issue given that it's not a time in which the tank healer or the tank is pressured.
What you need to take away from this is that WAR is going to be the absolute *king* of fights with regularly occurring burst damage mechanics like Caduceus, Titan, and Twintania *when played properly*. If you just use IB on CD, the WAR simply matches PLD. If you use IB right when it's needed most, you do a *hell* of a lot better. If you use IB at the exact *wrong* time, you're going to do a helluva lot worse.
The only times where this *isn't* going to be the case on a constant basis is when there is a CD active and, in those cases, we really care only about the burst damage aspect (since that's what you're using the CD to survive), and, at that point, it's largely about how often you can cover a burst phase with it:
For PLD, Rampart gives you one every 4, Sentinel is one every 6, Convalescence is one every 4, Foresight is one every 4 (with laughable contributions, but whatever), and Bulwark is one every 6.
For WAR, Foresight is one every 3, Convalescence is one every 4, Thrill of Battle is one every 6, Featherfoot is one every 4, and Vengeance is one every 4.
As such, WAR is going to be able to cover *more* of those burst iterations (number of phases totals to 1.25 whereas PLD gets 1.083) but the PLD will have much better contributions over time thanks to stronger effects and generally longer durations. I don't feel like doing the math on the mean contribution of each of those CDs while active and averaged over time, since it will pretty much have the same c
This further cements what seems to be the WAR's new intended role: burst damage mitigation. PLD will do *very* well as sustained high damage scenarios while WAR will excel at regular burst fights but only when played correctly. WAR is going to become the explicit skill tank; the tank that, when used properly, gives you *amazing* mitigation (which gives me a warm fuzzy feeling).