Originally Posted by hiccup
razer mice with the twin-eye sensor have negative acceleration aka "dynamic dpi-scaling"
No it's not negative but positive acceleration and yeah they all have this "feature" which is called dynamic dpi scaling.
It's all about the mouse automatically decreasing the DPI to very low values when you move the mouse slowly. I don't know specifically to which DPI setting it reduces it but I guess it's something between 100 - 400 DPI. So of course if you are using the mouse at 400 DPI anyway than you won't really notice it much. On the other hand if you use it at 2000 DPI for example then the difference is a lot and that big decrease in speed is really annoying when doing small/slow movements.
The only Razer mice with the PTE sensor that don't have this "feature" enabled are the Lachesis 4000 DPI and the original Mamba 3.5G with firmware version 1.06 or lower.
The more people who contact Razer to tell them they don't want that Dynamic DPI Scaling enabled the more likely it will be that they listen someday and release a firmware without that DPI Scaling. Until then I can only recommend to stay away from these products.