Gevlon's experiment is a bit more hard-core, but on Saturday we went into ICC-10 on a fun run, for alts and people who aren't raiding seriously. I let myself be talked out of tanking at first (I was on my pally, so I went LOLRET instead). We picked up a guildy on his alt DK tank plus a handful of other pugs.
The DK tank might have had more than 5K gearscore, but he'd have been the only one. We wiped a bit, but we got Marrowgar, Deathwhisper, and the gunship down and had a really fun time of it. By the time we got to Saurfang, we'd been at it a while and so only made one attempt before calling it.
We're going back next week without the DK, and I bet we do just as well and with even more lulz.