I’ll be brief:
Those who have a hissy fit over “under geared” players, you SHOULD already know that Blizzard has implemented their own gear check to ensure people don’t have gear that isn’t up to snuff for an instance. And I shall offer you proof.
Yesterday, one of our long standing guild mates finally dinged 80. Yes, it took him over a year, but real life gets in the way of WoW sometimes. Anyway, once we had enough people online, we decided to take him to a heroic. We had all opted for a random, knowing that it was likely going to be Utgarde Keep or Nexus and also give us a couple of EoF’s. But we ran into a little hiccup. It looked something like this:
See that there? We couldn’t even queue for a random heroic because our fresh 80 wasn’t adequately geared, as per Blizzard’s own gear check. So, we manually went and did HToC and ended up getting him two pieces of gear. And THEN we got to do our random Heroic, which was Utgarde Keep – and we got him a third new purple. It was pretty awesome.
So, this goes out to those jerkholes that seem to get their Spiderman underoos in a knot when they feel someone is “under geared”: Chill out and shut up. Sure, they may not have 3-4k dps, but there’s lots of “geared” players who can’t do that, either. And really, so what if a boss takes 55 seconds instead of 35 seconds? Everyone in that instance is adequately geared for it as well.
Thus, I say again – Chill out and shut up.
You’ll be fine.

Yes the gear check is there, however it seems rather lax. Just the other day I was tanking Heroic culling of strat, and a darling warlock in 50/50 greens/blues was with us. He topped 700dps with Rain of Fire.. fine, appaling DPS but CoS isn’t exactly hard so no bother. Still made the drake with 2mins to go.
However.. I was handed the short end of the vile ugly-stick by the LFG interface. My offspec is resto, and I sometimes heal some random hc’s when I get tired of staring at my own quite huge fuzzy bear butt. I was given heroic HoR, in my ‘poor’ gear. People laugh at me and doubt my healing abilities in Nexus before they see me in action! It was demoralising to see my party members drop one after another, dead on the floor.
Many a time have I recieved FoS/PoS/HoR as tank, where the healer drops group immediatly as we zone in saying “I can’t heal this, soz”. The three new ICC 5mans defenitly need tuning in the gear req.
I will agree that it is a little lax. I guess my biggest point of this is that everyone first trudged through 80′s heroics with anywhere from 800-1200 dps. It may have taken awhile and no achievements were acquired, but it was possible. So, for the most part, people having a snit about someone’s gear is often unwarranted.
In our case, all it took was two pieces of iLvL 219 gear and suddenly he was “okay” for heroics. Seems a little silly, but it’s also nice that Blizz is trying to prevent players from overestimating their limitations.
Now in the case of HoR, I think the hardest part about that is actually coordinating your DPS with the tank. I’ve tanked and DPS’ed it, and at least theoretically, DPS shouldn’t be taking TOO much damage if you’re coordinated and positioned well. But then again, those waves with all the ranged mobs are hell to maintain aggro with as a tank. It definitely helps to be “over geared” for that instance should things start to go south.