I've found the same thing you have with sks Vaindolf. I regularly group with an sk in volska's husk and the sk has 10k less hp slightly less hp about 2500 fewer aa's (has the same or lesser foci) but mitigates damage far better than I do. He can hold aggro when I keep white cons nearly chain stunned. Sks have better aggro, far better dps, and much better damage mitigation (be it lifetaps or whatever). So what am I good at? Keeping the sk alive on named with Aurora.
I don't want sks nerfed at all, but pallies need to be boosted closer to their level.