Hi, I'm having the same debate daily lol. In Cata I found Mr. Robot to be dead on every time, can't really think of an exception. After MoP hit things are different IMO. AMR still says that the "community's" preferred build is Mastery still, and completely drops hit/exp and "avoidance" in favor of Stam/Mast. I'm not going to list there "Avoidance" build as it doesn't seem as viable (YMMV)...
Currently there weights for the Mastery build are:
Stamina 1.74
Mastery 1.3
Strength 1.2
Dodge 1
Parry 1
Armor 0.4 Soft Cap Weight Hard Cap
Expertise 0.2 0.075 0.2 0.15
Physical Hit 0.2 0.075
And the Hit/Exp weights are:
Stamina 1.88
Mastery 1.3
Strength 1.2
Dodge 1
Parry 1
Armor 0.4 Soft Cap Weight Hard Cap
Expertise 0.2 0.075 0.2 0.15
Physical Hit 1.4 0.075
So, the bottom line for me. I've tried both, and I've tinkered with the weight's some. Using their Mastery Build I was over 150% mastery lol, lost a fair chunk of health, and had next to nothing for hit/exp. In Heroic 5 mans I could feel the difference, I can only describe it as "Squishy". This is with 100% uptime on Blood Shield and diseases. Then in LFR it was compounded far more IMO. Then in our weekly MV run, it just wasn't cutting it for me. Healers were going oom left and right, just not cool.
Long story short as I can. I played with the weight's some, tried to come to a compromise with the Stam and Mast, while adding back at least some hit/exp. I don't have the numbers for exactly where I ended up, I'm not EJ after all lol, but I tinkered. It fealt more or less the same frankly.
Going to the Hit/Exp Soft Cap however is a far far different ball game to me. I hit much harder, I get some glancing blows but pretty much never miss. My threat is SOOO much easier to maintain when dual tanking and swaping, before I had real problems getting agro back off the other tank, now it's instant snap agro on demand. My DPS, especially on AOE pulls normally tops the raids charts due to vengence, and I can only assume with an educated guess that is also why my Blood Shields seem to carry more weight. My stam is well over 700k buffed, and I can take the hit's (esp from Magic Bosses) where as before I'd get smacked down.
As I said I'm not EJ, I don't know nearly as much as a lot of folks. But from just my personal experience so far the Hit/Exp cap's are more important than people are giving credit for. It's night and day playing one build to the other, at least for me.
I'm curious what others have to say for input to this. I welcome any idea's on the weight's to balance things even better if someone has a suggestion. Attached below is my toon, I do swap out the glyphs and talents from time to time as I see fit. The gears ok, there is always better lol...
Azgalor - Tylerdurdens
Take care,
Tyler