Well I can tell you I can run Heroic Gundrak, Drak'Tharon, and UK with 0 issues and quite fast with 4 elemental shamans. I'm about to add Culling of Strat to the list which should be decently easy and then might try HoL. From everything I've heard about CoS and HoL they are easily doable with no resto shaman (and CoS would probably be easier to finish a 25 min timed run with 4 ele anyway).