I have a GX CS2 pump that I bought in January 4th, 2021. It appears to have lost the ability to hold pressure, as of April 13th, 2024. So a little over 3 years of solid use.
I did not use it very often but my usage could easily be called "hard", when it was used. I filled up two SCBA bottles with it, turning the pump on and off on a timer to keep the pump temperature down.
Sometime this summer I'll take the pump apart to see if it's an easy rebuild or not.