Please stop trying to run our forums for us. It's clearly obvious you have experience with the encounters and the ability to offer a lot to the discussion. However, you're subject to the exact same rules that everyone else has to follow and that includes reporting posts and letting the moderators decide what is relevant/irrelevant. Thanks.
These kind of posts are irrelevant. All you bring is anecdotal evidence that you think Mastery is better. There's no point in discussing this way if you can't bring solid proof to the table. While I can't log on to log out in my tanking gear right now, I can assure you that having tanked Ragnaros prenerf in both setups there was no noticeable difference in my damage income looking at it from an EH perspective going through my logs from back then. Our problems are not something we can accommodate by using different gems or reforging. They are issues with core mechanics of the class which are obviously being looked into for the next tier. For now, just do whatever you feel most comfortable with, I can assure you that you barely will notice the difference granted you play like you should in both scenarios (timing DS's, keeping BB up and all that good jazz).