any razer mouse has this i'd say... this is built in the firmware and has nothing to do with things lik enhance pointer precision :z.

I noticed weird tracking errors like this in my DA tests, but never noticed them with the DB3G or the Habu TBH.

I'd say the IME 3.0 is still the best way to go if you're a low sense player.
High sense players aren't having a very good season...

I use my Habu on a Steelpad 3S, and 4D

3S is a metal pad, so it won't really get broken in.
The SteelSeries SX was notably bad for my mice, so I don't think that's a good way to go.

The tracking is better on the 3S, but the lift off is better on the 4D...but I don't notice this off center problem affecting my tracking, even though the sensor is lower than the center of the mouse.

I do feel like the Habu is the best high sense mouse around...but you may also want to try the new BlueTrack Sidewinder X8 from Microsoft when it comes out, since it will use a new tracking technology...I hate wireless mice and their lag, but maybe if you leave it connected with the wire, it won't have that problem. That combined with you can't program the five extra buttons the mouse has leave it as a very overpriced product in my opinion. (the 4 below the scroll wheel, and the 1 above the two side buttons.)

Is this a widespread problem or just a few unlucky units? 

Thinking of a getting a DA (for vista 64bit & goliathus).

Razer has stopped answering my emails, I guess they don't care about their community members.

After reading this I'm definitely going for Microsoft IntelliMouse 3.0. It makes a huge difference in gaming.

I contacted Razer support and asked if updated firmware would be available to fix this. Their answer boiled down to, "we don't know what you're talking about now go away."

Sounds likely.  We need to dream up a repeatable test in order to measure how much each sensor is affected by this.  It might not even be intentional - it could just be the way the mouse tries to track movement that causes the problem.