I've used the Logitech MX518 for more than 5-6 years, and the G502 now is about the same age. I stopped using the MX518 because I wanted a change. I got bored of the MX518. The two other mice I bought, broke or developed double-clicking issues in a year each.
I love how the G502 performs, but I'm developing that tingling sensation of wanting to use an alternative but a lighter wireless mouse, maybe the Logitech G304/305. Let's see.