I just looked through our log once again, because I was curious what the average of our DPS was. Leaving out our tanks and healers and only looking at damage dealers, the average was like ~19460 and we had 12 secs left till enrage. (Though both of our melee camps died at about ~4:30-4:40)
I thought the 19.5k that was mentioned here was pretty high so I was quite suprised we were exactly at 19.5k! (I actually thought we were lower)
About Elemental... both of us did about 20k dps (usually just a little above 20k) at our butcher tries and I was at ilvl 636 and our other Ele at 642. (Though I actually sim higher dps-wise, because I got a whole bunch of sockets on my hc dungeon gear, so I guess you could say we were both roughly at 640.) Actually on our kill try we both dropped down to ~19.1k and 19.5k (There it is again! The magical number!) because we were standing in the melee camps and died at the end. But anyway, 20k is really not impossible.
If you have so many people whose gear is below 635 and who can't get the damage done, I'd really say: Grab some gear and try again next week. Normal is doable in that gear and you'll manage to get quite a few upgrades. Maybe to everyone on his own the one item he grabs, doesn't make a difference. But if you consider the whole raid and all the items dropped, that's actually a huge improvement!