My guild is running Ulduar(10) on a weekly basis now. We have downed all bosses (including ignis) up to Auriaya with I would say is a group who is the right gear lvl for it. Both tanks (including myself) have 4200 gearscore and the healers have 4000-4200.
Last night we tried to do Thorim but we just couldn't get him down. Most of the attempts our group two never made it out of the gauntlet, or group one in arena died before group two was out of the gauntlet. The mobs in the arena were just piling up, I think at one point when the group two had just gotten to second sub-boss I must have had at least a minutes worth of spawns on me in arena. So I think that the dps in both arena and gauntlet was lacking because in the videos that I've seen the mobs in the arena don't stay past one wave.
Currently we are running with a few who have 3400-3600 gear score and even though they may be skilled I am not sure that it is enough to get bosses like Thorim down.
My question is: How much dps do you need to have when you get into the later bosses in Ulduar(10)?
Edit: Clarifications The gearscores are from the GearScore addon, as a reference 4150 is recommended for ToC(10). Our tanks and healers far outgear Ulduar(10) but our dps is in the 3400-3600 range, 3800 is recommended for Ulduar(10).
We split our raid like:
Group1: Arena Group Paladin(me) - Tank, Shamman - Healer, Druid - Healer, Paladin - DPS, Hunter
Group2: Gauntlet Group Druid - Tank, Shamman - Healer, Rogue, Hunter, Warlock
Edit #2: We Downed Him
Last night my guild went back into Ulduar to see if we could get Thorim down before it reset, we got him down in 4 attempts. We tried having me in the gauntlet and our druid heal while our shaman got on her pally and tanked the arena but no luck. So on our last attmept of the night the druid switched to feral and tanked gauntlet, the pally tank got on her shammy and healed arena, and I tanked the arena. Thank you everyone for your imput and advice, it really helped.
Group1: Arena Group Paladin(me) - Tank, Shamman - Healer, Shamman - Healer, Paladin - DPS, Hunter
Group2: Gauntlet Group Druid - Tank, Priest - Healer, Druid - DPS, Mage, DK