Now you have to understand that I have never even seen the inside of naxx before. My guild pre-bc was a ZG/MC guild and that was about it, and I never went there during BC pugs. My experience was just WOW though. I loved it. HUGE instance. TONS of bosses. Boss mechanics you cannot find anywhere else (a boss where you MC a minion and have them tank? come on! cool!). That said I must stress the need to be hit capped and expertise capped BEFORE you raid, at least those of you DKs that are planning on dpsing.
We need to be at the specials hit cap, which is 9% or 295 rating, and expertise cap, which is 6.5% (I'm told) or 26 expertise. I'm personally a little over on expertise, but I can't help it right now.
As far as actual dps, I compared myself to a guild rogue as he would be in the same situation I am, having to move out of melee range, or stand by and watch whirlwinding mobs and dps pretty much the same thing I was. In most situations I was very last on dps. The only time I really ever beat anyone was on this boss that had a living side and a dead side. The rogue was top dps, I was second, and then everyone else was below me. I pull an average of 1500 dps in greens and blues, while our other raiders (granted, they were mostly in T6 raiding gear) were pulling 1800-2000.
I'm fine with that though, I so enjoy death knight to where I don't really care where I am on the charts, the class is just fun. Plus having a DK on this boss where you had to pull an add next to the boss before killing it, that mechanic was made silly easy with a DK. Sit there dpsing until it's time to pull the mob over, deathgrip, dps, and win.