so how important is it to get 2 or 4 piece shadow? what is the damg increase for each? i am stuck on whether to craft the legs and buy t11 glove (already have shoulders) or just leave out and get 4 piece eventually.
I don't rate the 4 piece at all to be honest. Its not like the pieces are bad though, so get it if you have nice token drops. At the moment though I'm happy to pass conqueror tokens to locks and paladins as my offset gear is just as good.
Looking at your armory you are yet to buy the T11 Chest. Make that your first priority with valour spending. Getting the 2 part bonus with Chest/Shoulders is pretty much the ideal when you consider the alternatives.
In terms of the 4 piece bonus there really isnt the stats on non tier gear to equal the dps the bonus generates so eventually you will want to be aiming for it.
2piece is about twice as valuable as 4piece, which comes out to (basically) if you have 359 gloves/shoulder/helm to make your 4piece bonus (or as a 3rd piece, even) and a 372 replacement comes along for any of those slots you should take it because it will be a DPS increase.
The 4 piece bonus is worth aiming for, as 3 of the T11 pieces are BiS anyway (maybe 4 now, with 4.0.6). The actual benefit of the bonus isn't massive, but it definately outweighs the slight stat boost you may get from a better non-set piece, especially on movement heavy fights.
^ This is talking about normal or heroic gear only, not mixing the two. I'm not sure on the specifics of a heroic piece benefit over 4 set bonus.