To begin with the mouse was tested on both hard, soft and desk surfaces. The Philips Twin-eye sensor performs well on pretty much all surfaces however the lift-off distance varies a bit.
In terms of feel the new Lachesis is just like the old one. The exterior design has not been altered noticeably apart from the side buttons and the scroll wheel. The bulbous shape means that it is intended for people who mainly use the tip of their fingers to control the movement of the mouse. If you are used to palm grip type designs it will feel very odd to begin with.
One of the major performance issues of the old design is still present on the updated version. We are of course talking about the erratic tracking during lifts. This is an issue with all Philips Twin-eye based mice and while the lift of distance is very low ~2 mm it is still very annoying especially at high sensitivity. Of course you do not lift the mouse that many times when you are using a high sensitivity but it is still very annoying. The small teflon patch around the sensor is most likely there to reduce the amount of Z-axis tracking on really soft mats.
As with most modern laser based mice it can keep track of even the fastest movements at all sensitivity settings. The sensor scales brilliantly which is great because it means that you have a lot of different settings to play with. There is of course only one annoying detail and that is that the Windows sensitivity adjustment is not available through the driver suite. The old Lachesis did not feel quite as precise as the Agilent 9500 based mice. It seems that the new sensor has fixed many of the bugs that where present on the Twin-eye sensors while they were still in their infancy. In terms of absolute precision it is still a bit behind mice like the Mionix Naos 5000 or SteelSeries Xai, which we suppose is due to a small amount of angle snapping / prediction on the Lachesis.
With a maximum DPI setting of a whooping 5600 DPI you will never run out of resolution, not even on a Eyefinity setup. Once you set the DPI to maximum you will have to dial down the Windows sensitivity as well as the in-game sensitivity in order for it to be controllable. Even at a high sensitivity the mouse feels manageable except for when you pick it up. Despite the odd tracking errors during lifts the mouse performs brilliantly, and after a week of serious gaming even the shape begins to make some sense.
Driver
The Razer driver suite functions pretty good, however, the omission of Windows sensitivity control from the suite is annoying.
As with all the other high end mice from Razer this one supports different profiles and has a fully fledged macro system that lets you assign all sorts of functions to whatever button you like.
The new Lachesis has a two zone light system that lets you select the color. The integration of this new feature to the mouse is seamless and it has out favorite setting, off!