How much mastery is too much mastery?

[Calleana]

I think it depends on what you are doing, in heroics hit/exp seems a bit more important as you are unlikely to have tricks or MD and dps is a little more trigger happy.

I've only recently taken the brave step to reforge hit/expertise to mastery and I am noticing the lower threat but hopefully I am easier to heal and not currently threat capping dps so think it was the right move.