I have something to point out, in your assumptions.
First off, I would like to see logs of tanks doing 1.2k DPS. I can push 950 DPS, and I don't see how the 4 pieces of 72 gear I'm missing will up it to 1.2k. I don't think using Styrak as an example is a proper comparison; nevermind the fact that it's a different fight, there is an increased damage phase, during which all DPS is boosted.
Secondly, especially since you advocate keeping all three as close together as possible, to minimize time spent switching, we have to discount the DPS generated from AOE attacks. While for some classes AOE attacks (controllable or not) make up a small portion of overal DPS, for others it's larger. Regardless of the fact, all AOE DPS has to be subtracted from what is actually presented through combat parsing, since all of that damage is negated every time one of them die.
I'm no math expert to run the numbers and see what's being lost there, but between that and the need to be absolutely perfect in execution, I am also inclined to believe that it is slightly overtuned. After all, the reality of the current situation is that guilds are hitting enrage timers hard. If a simulated model does not represent the reality of the encounter, then the model has to be incorrect.