I tried Ravana EX the other day, we didn't clear it, but to my happiness it is puggable in DF (the lowest we got was 3% before people's gear started breaking)
I'll be running the crap out of it because the Ravana bird is the exact shade of red and black that suits a DRK.
these look awesome compared to the old ponies. can't wait to see what mount we'll get for collecting all of them again.
They're nice - though I won't bother trying to get them until later in the expansion when the drop rate is increased and/or the item level difference is greater so it's more efficient and less time consuming to farm them.