For everyone who was demanding proof in this thread:

We now have a way to see this, using microe's mouse tester program:

The FinalMouse is the only sensor I've used that has matched the MLT04 as far as accuracy & responsiveness is concerned. So lets take a look at what its graph looks like:

Now lets look at some comparisons I did after detecting some tracking issues in game:

Now keeping in mind how much the (somewhat minor in comparison) deviation shown there made a significant difference in game, lets look at the graphs of the g502 and FK1 (both of which I previously said were shit, with the 502 being somewhat less shit):



See how much they deviate from the line?

P.S. - This isn't perfect, as the graph doesn't really show how the mouse feels ingame (IE: the deviations on the FM graphs were evidence of a different feeling/problem vs what was felt with the other mice). But it does give us some evidence of flaws we can feel while playing.

Many thanks to Microe for his program, and Ino for his screenshots.