I guess i'll say this now, current lists have been made for specs which are considered competitive in a challenge mode environment where the goal is to get the FASTEST possible time (though please don't consider this that getting full BiS gear will guarantee you to grab a top time, gear helps a good amount, but a lot more of it comes down to the strategy performed for the run). I also personally don't want to go into the extent of making every class' specs for a Challenge Mode/Proving Ground environment, purely cause i'm lazy and i'm very limited on my own knowledge for multiple specs as it is and i'm unsure on the others which also have contributed to the spreadsheet on how far their knowledge on other classes goes. Feel free to throw your own lists if you want into this thread if you want to contribute for your own class/spec communities for anybody who may say are after better times, weather it is trying to compete for Realm Bests/World Bests or you just want to improve your times for the fun of it.
I believe the Lei Shen mace is BiS for Disc. It has a Red Socket (+60 int bonus) and the stat weight budgets more towards Int than secondaries giving the mace +80 intellect at 463 iLvl, for a total of 140 extra Int over the wand. It works out to be 140 Int vs 160 crit/haste mix I believe, and I think the int wins there.
http://eu.battle.net/wow/en/characte...v%C3%A1/simple This is the armory of the mage from the best team in the world. Gear with hit ranges from 489 to 561 in ilvl, and few of the pieces are upgraded, which would increase the hit even further.
Basically, you don't get "free hit" from items with more hit on them. It just compensates. The biggest thing about gear is to just get items with as many sockets as possible (because losing secondary at least for a spriest is worth it for the gem slot) and right itemization. Ilvl does not matter.