One very common question is how much hit rating does a dual-wielding character need? My Hit Caps Guide only lists the actual cap, and doesn't address whether going for the cap is a good idea or not.
Basically, after you reach 9%, hit rating only affects a portion of your damage. However, hit rating is cheaper than crit rating. So how does that balance out?
It depends on how much white damage you do. As a general rule, with the current costs of hit and crit rating, you need about 65-70% of your damage to come from auto-attacks for hit rating to outweigh crit rating. However, you also have to take into account special abilities that may come from white hits.
Baseline, most melee classes get about 50% of their damage from auto-attack (white damage) and 50% from specials (yellow damage). Each class does have unique aspects though. Please note that you must get at least 9% hit so your specials never miss. This really concerns the range from 9% to 28%.
The most powerful finisher is Slice and Dice, which speeds up auto-attacks by 30% (equivalent to increasing auto-attack damage by 30%). This pushes rogues into the range where hit rating becomes worthwhile. Additionally, Combat rogues get extra energy from off-hand strikes, through Combat Potency, making it additionally important that their white attacks hit.
Thus the accepted wisdom for rogues, especially combat rogues, is to try and reach the hit rating cap, choosing equal values of hit over crit.
Fury warriors often use Heroic Strike, which converts your next white attack into a special, using the miss rate for specials. This actually pushes the proportion of white damage down, and makes crit a better option.
Auto-attacks do provide rage, so hit rating shouldn't be completely scoffed at. Don't go out of the way to pick up hit rating, but most warriors tend to have a bit more than the minimum.
Enhancement Shamans again have about 50% of their damage coming from auto-attack. However, unlike warriors and rogues, shamans don't get rage or energy from their white attacks. The only other consideration is Windfury, which procs off auto-attacks. Windfury has an internal cooldown, however, so hitting more often does not really increase the number of procs.
So shamans are generally safe in ignoring extra hit rating and going for crit rating and attack power.
No. Just No.