Well, that was both an enlightening and painful read. The amount of people who when shown math and and obvious facts who repute them is amazing. At the same time the 3-5 people doing the bulk of the theory craft are doing a good job.
Here a few of the better posts. Ghost makes his post on page 15 so I would recommend starting there. Can't find the link to the antitank set and don't want to have to read through any more o-boards threads today.
This one and the next few have some good simulations of how the shield will work.
Has a few good ones here, showing a Patch type boss and Maexxna style with stuns.
The simulations are using an 'antitank' set which would become the new tank set. Has a greater emphasis on AP, crit, expertise, hit and haste than the current gear methodology. Hurray for more tank DPS and same mitigation.
Overall the change should be a slight buff in most situations. In general the change is minimal. Still not thrilled about learning block, just for flavor/lore reasons. The additional scalars will be a great help as otherwise we would have been shafted by DRs come Uldar.