From what I'm reading about hit/exp for tanks most players don't seem to be going for those caps as they want to focus more on survivability especially for raiding. With the Vengeance buff we have as tanks threat should never be an issue assuming that you are also using the correct rotations.
The only reason why I'd go for hit/exp cap is rage generation but I don't know how much hit rating would affect that. I would probably have higher avoidance if I didn't reforge for those stats.
But as for my stats:
My dodge/parry would be higher if I did not reforge for hit/exp, and also enchant/gemming