Me and a friend had a playtest yesterday, he ran the standard 5 man team at the encounter (warlord, no cleric) and got bogged down in the south side tunnels and then Irontooth got involved and cut them to ribbons, even so it was fairly close, at one point the next hit would have dropped him. The real spoiler for them in the fight was that Wyrmpreist who shot them to bits.
My friend ranted for a little while, then we traded places and I had a go, I took a six man party in (cleric AND Warlord). After a hard fight we got to chase that *&*$ Wyrmpriest around the tunnels to finish him off. No losses on my part and everyone but the Wizard and the Fighter spent time on the floor (two deathmarks each for the Warlord and Rogue).
It's a hard fight, but my friend even while bitter about the overstatted encounter seemed to enjoy it. I now have a definite respect for the power of higher level monsters, particularly elites.