Well, for now at least, I'm giving up on the Razer Death Adder. I've replaced the horrible stock mousefeet with the Hyperglides I ordered from overseas, so that's good, but ...

I'm still getting the 'stair effect' in paint with it, and I also have some weird delay that feels a lot like mouse smoothing. I don't actually have smoothing enabled in the razer drivers nor any of my games. I have tried running it without installing the drivers but that delay is still there. It's most noticeable when using the railgun, as I'm primarily a flick shot railer.
The easiest way to describe what it feels like when railing with the D.A. is to compare it to Quake 2's railgun. There's that momentary delay between pressing the button and the actual rail firing. It feels just like that, but it's doing this in Q3 and Q4.

I know that a lot of people use this mouse, and if there's an actual fix I'd love to hear about it. In the meantime I'm back to using my I.E. 3.0 @ 500hz.