Recs.
Updated
The Proteus Spectrum gaming mouse is the updated version of the Proteus Core. Its weight door has no blue accent and the G light can change colors. All other specs are identical to the previous model.
SpecsUpdate
Pros
Pro Highly customizable gaming mouse
The G502 gaming mouse has 11 programmable buttons: Left, right and middle click as standard PLUS 3 thumb buttons, 2 on the side of left click and one behind the mouse wheel. On top of this, the mouse wheel can tilt left or right for extra functions. All of these buttons can be binded to do pretty much whatever you want. You can also customize the weight of the gaming mouse to adjust how it feels to move across your mousepad.
Pro Highly customizable
The G502 gaming mouse has 11 programmable buttons, support for macros and profiles, adjustable weight and center of balance, two scroll wheel modes, and a plethora of settings to customize.
In addition to the standard left, right, and scroll wheel buttons, there's a button below the scroll wheel, three thumb buttons, two buttons to the left of the left mouse button and you can tilt the mouse wheel left and right for extra functionality as well. All of these buttons can be programmed to do pretty much whatever you want.
The scroll wheel can act as a smooth unhindered scroll or a notched scroll depending on how you want to use it.
It has an on-the-fly CPI switch with 5 states and the mouse can store three different macro profiles and can switch between them with a button press.
You can also customize the weight of the gaming mouse between 121-139 grams and its center of balance with up to five 3.6 gram weights to adjust how it feels as it moves across your mousepad.
Pro Scroll has horizontal clicks
The scroll wheel can be pressed from side to side to enact two different programmable button presses.
Pro A really impressive software support
The logitech gaming software and logitech gaming hub are one of the best softwares for peripheral support. You get a heap amount of options and customization options such as full macro setup, option to switch between on-board or software controlled memory, custom acceleration, key press statistics, analytics for game-to-game based macros and much more.
Cons
Con Can get uncomfortable after long usage due to weight and shape (especially for larger hands)
The mouse weight is already a lot, but for better upward and downward weight distribution, it asks you to insert at least 2 weights in. The shape, however is very much based on hand size and angle preference.
Con Software doesn't support Linux
LGS (Logitech Gaming Software) does not have Linux support, so the mouse cannot be tuned or configured under Linux. However, if the mouse is configured on a different OS, the configuration will work on Linux, since the profiles are stored on the mouse itself.
Con The position and sensitivity of the 1st thumb button makes it accidentally pressable, especially for big handed users
Con Potential pinning bug
Changing the surface setting in the app may potentially cause random spinning ingame for a random period of time (usually ~5sec). This has something to do with the surface of the mousepad being used and a particular setting of the mouse. In order to address this issue, you can return the mouse back to its default surface setting.
Con The LED behind the G is really bright (can be disabled though)
The LED backlit G on the back of the mouse can be quite bright in a dark room. For users that do not want to use the application that is necessary (or can't, like say Linux users) the light is unable to be turned off. Of course within the application for the mouse the light may be completely turned off.
Edit: It is a problem in Linux only software can be used to control the brightness of the light.