Regarding the Deathadder vs Lachesis... I still use an old skool Boomslang at home and a bog standard mouse at work, so I can adapt to ergonomics effortlessly; however, I recently had a DA. Obviously, moving from the Boomslang to the DA was a change, but no challenge.

Regarding the DA specifically, fairly comfortably, and relatively small and light compared to what I'm used to. Excellent performance wrt sensor. Main mouse buttons were good, placement of nearest side button was good, but had to reach for the front one. Here comes the but... DA broke after about a month. Booted up one day and it wouldn't respond and Windows reported it as a faulty USB device.

So I'm looking again... I was tempted to get another, however, I decided to wait until the Lachesis came out so assess options. I am drawn to the Lachesis because it has 9 buttons vs 5 on the DA (main reason), and the shape is closer to the BS, which I'm very used to.

I'm also keeping half an eye on the SteelSeries Ikari Optical mouse (I won't touch a 1st or 2nd generation laser mouse), but I'm put off by the lack of buttons.