I don't really see what so much better in lachesis than in mx518. The mx 518 works great without any quarks but my lachesis somedays didnt want to work across the entire monitor. Felt like it was stuck in a box until i repluged it, the precision was not good either at all cus it felt like i was painting in mspaint where the line was very blocky/pixelated.
Sometimes the scroll button stoped working in win. Of course i flashed it to the latest firmware at the time to 1.6 and one time i found that it had reflashed itself to 1.8 without me doing anything at all. I couldnt even find that version on razors site, but it worked great as it should from then but it still didn't feel smooth at all in movements.
How could you say that it is a top notch product when even my pals have similar problems. and let not forget that the mouse pointer sometimes wandered of on it own to the left sometimes. maybe if the quality checks were better i could say that it is a top product.