Ok, here is the promised report..... it's a bit late, as it was done before patch 4.0. Whatever.
Apparently it's a tradition on our server, a "full-drood raid" is done at the end of every raid tier, abusing the fact that druids are the only class which can fill all the possible raid slots. I've never found myself in one of the old raids (I remember something about one in Ulduar, but I was already tagged for the week). In any case, on a saturday evening we ventured into ICC10 as a full druid raid group (with some unhappyness from the various guild's raid leaders which found themselves with a lot of unavailable druids for the current tag).
Standard composition: 2 tanks, 3 healers (one with moonkin spec), 5 DPS (3+2, I was one of the cats).
Now, even if the druids can fill the roles, it doesn't mean they are optimized to fill the role..... in particular there are some glaring holes in the abilities which are around. For example, a lot of missing buffs: some of them can be replaced with drums/scrolls, but things like resistance auras are not that easily replaced. It also means no MD/Tricks (= hard time for the tanks to keep aggro). More serious: it means no slowing effects and NO DISPEL DISEASE. This last one can be troublesome.....
The idea was "one long eveining, as much HM bosses as possible, but we want to get to Arthas". So we started with Marrowgar, which was unsurprisingly one-shotted in HM. We were not that sure about Deathwhisper HM, but it went well and we one-shotted it as well. After all the only real trouble are the curse (we can dispel) and the mind control (cyclone says hello). Gunship battle was a joke as usual.
The we got to Saurfang and things turned to be a bit harder. In particular add management.... full druid means we have no slowing effects, unless someone goes around hitting them with Infected Wounds our stunning them with bash. They both are hard and/or dangerous to place, since in HM there's the -80% movement speed debuff, so we kept losing people to the adds. One mistake and we had one ranged dead.... The solution was for us cats to start spamming Roots on the adds as soon as it was safe (= not in melee range of anything). Sure, Roots breaks fast, but it turns out that if you frantically press the "cast Roots" button, the mob is almost unable to move, as it's re-rooted as soon as the damage frees it. Add to this some ferals (ahem ahem) taking aggro and dying and in a few tries we had it down. 4/4 HM!
Next step: Blood Wing. No trouble, I think we did one wipe on Princes due to the Keleseth tank getting gibbed, but the two fights don't have any mechanics that a druid can't handle. 6/6 HM.
Next: Plague Wing. We get Festergut down fast (one or two wipes due to some mess at range, I think), then on to Rotface. As it turns out, Rotface without dispel disease is not the same thing as the Rotface Achievement.... The disease does a lot of damage and places a healing debuff, so we ended up losing people. Now, with 10 battle-rez in the group this is not too much of an issue, but you end up with blobs all over and while the fight started always well, it always ended bad. After a few tries and a wipe at 1%, we decided to pass it in normal mode, not to waste too much time. Normal mode was a joke, of course. Putricide: we forgot to switch HM on and with the fight running and the few Rotface wipes still in our thoughts, we decided to pass it in normal mode, having no trouble whatsoever. 9/7 HM.
Finally Frost Wing. HM Valithria posed more problem that it should have, healing was taking too long and we were overrun by adds a few times. Still, we kept going and after a few tries we managed it. Sindragosa HM was too much. Too much damage? Not really. Too much DPS taking aggro and having her breath on the raid? Nope. It was just too late in the night (after 1am), we had been raiding since the end of the afternoon, and mistakes started to pile up. And when the mistake is that one tomb "disappears" 1 second before the last blast takes place, that's "BOOM half-raid-dead"-time. After a few tries we gave up and wanting to do some tries on Arthas we downed her in normal mode. 11/8 HM.
Arthas turned out to be a problem bigger than expected. Apart from being almost 2am, with everyone tired, Arthas without dispel disease is an Hard Mode by itself. We decided not to spread the plague to the adds, to avoid the risk of having it kill the add tank, which would result in an instant wipe. We cannot set-up a ton of tanks for the adds, otherwise we end up with no DPS on the boss. We tried some gimmicks (like potions), but there's no realiable way to deal with the plague except death+battle rez. We managed to reach the transition once, but it was somewhat unplanned, so we ended up with three Horrors (and no easy way to stun or dis-enrage them), being forced to AoE them down since we didn't have the plague to kill them reliably.
Unfortunately we were unable to find another everning when everyone was available, so we stopped after these few tries. The conclusion is that it's probably doable, with some luck in phase 1. Of corse now, with the 30 min CD on battle rez some tricks will be a lot less easy to do (BTW worst idea ever, since it won't stop people from waiting, they should have just made it "once per combat" end of story).
Obligatory screen of the last boss we managed: