Well personally I dont worry about it. I see alot of people that do but blizzard has made it so that you can avoid losing agro in the begining of most fights with misdirect. Generally i have about 4% on raids and that includes having a shaman in my group for the extra 1%. However I have tanked before with 2-3% no problem. I think the best thing to do is see how much TPS you can sustain, if its to low raise your hit. If you can sustain a decent amount of TPS I really see no need in sacraficing other stats for +hit.
I usually run around with ~4%. However, last night on VR I had it as high as 5.4%, and I still saw ~2% miss rate (not including parries/dodges). Probably just bad luck, but I'm definitely looking to up my +hit a bit more.
Your last 1% hit is just as good as your first 1% until you reach the hit cap. So keep piling it on unless you need the other stats.