Well, 1d wasn't very hard and 2d was doable. So my guild thought we should get to doing the real thing and tried 3d the other night. As you might imagine it turned into a 3 hour wipefest. This didn't make me (or anyone else I think) cranky tho. I wasn't really expecting to succeed (well deep inside I did or I wouldn't have tried) since it's one, or the one, most difficult encounter in the game so far. I actually had fun, because it finally gave me something to work with as a healer. Most encounters are fairly easy, and I dare say that most times we fail on something (which we rarely do nowaday, as naxx and everything is easy) it's not because of the healers (me), but because people stand in one-shot areas. Like the purple thingys on KT. Yeah, always blame the dps ;)
As for sarth 3d I think we all were on the same level of goodness (or badness, seeing as we failed). Yeah the dps was slightly low, but you can't do much about the gear in that situation. We tried some different compilations and the one I think worked the best was 2 healers, 3 tanks, 5 dps.
So we all basically had to try out different positioning and control-methods. Everytime we learned a little bit more about how to dodge waves, how to pick up adds, how to heal the tanks etc and so it felt ok to wipe.