5 Tries on Anub - Best at 37%.
Even if I dual tank I grab everything with my MT and it just goes smoothly. I spread raid in a semi circle in front of boss and tank everything in the middle.
It's the swarm that kills me due to silence. If I'm not mistaken the DK (nor the Pala) just can't use runes and therefore he has lousy avoidance stats. Aggro isn't a problem, I just die ^^.

5 Tries on Patchwerk - Best at 21%
Extremely easy fight. It just shows I'm not geared for it. I haven't updated my gems and DK is crittable (535 Def). I also do everything without food nor elixir buffs. Just isn't worth it while I learn the fights.
Started by keeping the two tanks alive (I only have two healers) and my best was at 47%.
Put Pala healing (humiliation lesson to a tank!) and just kept DK topped. It went pretty well. Raid is doing around 20k dps on this fight. The shaman are all above 3k (one at almost 4k) but Mage and Moonkin are around 2.5-2.7k.
Another issue I have is that both healers are recent lvl 80 as well as Mage and Moonkin. I have to do more heroics with them to get some gear but I'm pretty happy with the performance so far nevertheless.

As a note, trash is ridiculously easy so far.