Originally Posted by Zalinda

Getting back to delukz' question

(major part of discussion edited out for this reply -- good remarks, though!)

Being over the cap in anything can sometimes be a good thing if a certain mob mechanic reduces your abilities.
A mob doing a stat reduction could change things, as you loose Str (parry) and agi (dodge).
There have also been mobs with a higher-than-normal chance to hit.
I'm not sure if either of the above occurs in Cata instances/raids.
In any case it has in the past sometimes been beneficial to be slightly over cap, I'm unsure if such cases exist in Cataclysm content.