Why the old G502? From what I hear it's no longer being produced and taken off the marked in favour of the new RGB G502, which is basically the same, just more widely available and therefore cheaper, besides the RGB part.
I have the g502 for about 3 months now and am looking to replace it already, logitech needs to fix a lot of issues with it before people should invest in this massdrop
ourobros despite the fact that it is not so cheap is the best out of all i think . 2 different sensors+flexibility of shape + macros + lighting at night makes it a great deal