You would think this would help but that's not it at all. I remember my first time running CoF, I was a guardian in a group of 4 more ele's. It took us about 45-50 minutes to get through the path all up until the boss (granted there were other first timers as well); so you could tell we werent doing so hot. At the last boss, our entire team did absolutely NO DPS whatsoever; and the guy just kept healing to full. Being fed up, two ele's left and we were able to replace them with 2 zerker warriors, after which we facerolled the boss in 30 seconds. I think warrior's just need to be nerfed. This is exactly what Anet didn't want: one class being so OP that a dungeon group can't proceed without one of it.
I had a pug group in CoE that completed all three paths with relative ease using a zerker ranger and 4 ele's. By dumb pug luck one of the ele's was an experienced tanking spec and even though we had never run together we made the task look easy due to luck in team composition and the fact we all had CoE experience. So you can't really use pug experiences to create and pull consistent data from.
The most important thing in any dungeon run is experience. Experience trumps all. Knowing what to expect and how to manipulate your build and play style to suite a given environment is extremely important.
What comes next is having the group meet a respectable dps threshold. This allows the group to take less damage, feel like they are making progress and to be able to kill.
Step three is working as a team. Timely rezzing, group combos, using builds that compliment the situation and each-other, using voice and playing with the same group of people on a regular basis.
Once you have those three basic prerequisites fulfilled (the first two being the most important) the group can move onto mastering the meta-game. This is where you'll see the unholy trinity and dps shine.