Paragon have shown that they are definitely the rulers of ICC by proving that the Lich King can be defeated on 25 Heroic without the assistance of the ICC raid buff.
According to Xenophics, "We wanted to see if Lich King with 0% zone buff awards an achievement or extra loot, but the only cool thing was getting the caster sword (Bloodsurge, Kel'Thuzad's Blade of Agony) for the first time (x2). Decided to try this for the first time this week and used around 2 hours to get it done. We had Nakkimon disconnecting in the beginning of the fight so we ended up doing it 24-man. The encounter wasn't that challenging, the only problem was getting everyone to stay online the whole encounter."