Actually I wouldn't place shammy/warrior at 1st place of difficulty. There are other hard setups with locks for example. We've been going great at last battles with this combo, both at 1800 bracket last season (almost all of them with s3 shoulders) and we've not lost any matches at this season.
All you need is good communication and timing with your partner for the interrupts. Shammy won't go oom if he knows what he's doing, you need to end windfury/poison cleansing/mana regen totems, and use your rogue's sap/blind as soon as possible. Usually a good maim/kick/charge/KS combo can leave a shammy unhealed.
A mutilate rogue sounds more fun, but..... that cheat death and double evasion/vanish is cooool.
Except if your partner is Boozt.