As it sits right now, my 10 man group is one kill away from the Champion of Ulduar achievment - which while significantly easier than Undying or Immortal - still poses a problem.
See right now we're working on three things in 10s. Server first Algalon, server first Firefighter (which leads to Algalon), and server first Rusted Proto-Drakes. The problem is, we can't do both at the same time. In order to complete Glory of the Ulduar Raider, we have to work on One Light in the Darkness. Now, while we 'could' in theory one shot that event with nobody dying, I don't think that's going to happen. Because we can't send keepers back up however, we can't take our shot at a flawless kill - and then work on the rest after.
I think this is why I like the new 4 lockouts available for the upcoming raids. You can get your feet wet and learn the bosses on the normal lockout, then get your game on in the heroic. Folks might get burnt out faster - I don't know. I'm pretty sure that those I raid with won't though.
My biggest concern is that they'll be dragging my healing butt through heroics and Naxx on their alts for badges. I seem to be disconnecting......