Razer Deathadder or Lachesis?

Both are good, go with the cheaper option.

PS 5600dpi is useless, I have used the Lachesis and also a logitech g700 (g700 was much better)

At a insanely high dpi setting, it moves too fast to be useful for anything other than wanting to spin around quickly in order to look silly to team members in a FPS game.

also 1000hz USB reporting causes a higher CPU usage with with little to no noticable improvement in perceived performance of the mouse.

i'd go with the cheaper one, i've got a lachesis, and after 2 years of use it's starting to show signs of ware, the rubbers coming off the top to expose bare plastic, the middle roller click is broken, the side buttons are barly usable.

i had a cheap A4tech mouse i bought ages about that lasted 3 years befor it started to show signs of a button going down.

the changeing of the resoluton of the sensor to speed up or slow down the mouse, i've hardly ever used, even in game, maybe used it a few times. the only good thing about the settings is that you can customizie it to your likeing.

it's a good mouse, probably for a larger hand as it's quite big.

I've used the Deathadder for at least 2 years of intense gaming. It's such a flawless mouse. I mainly used the scroll wheel and it never failed on me, even after close to a million scrolls.

Personally, I would recommend the Razer Imperator. That's the current one I have right now and it's a great step-up from the Deathadder.