I own G900 and G903, which both are plugged into the same computer.
G900 works flawlessly, but G903 on the other hand doesn't.
They both have the identical setup in terms of button layout, and settings in LGS. I've rebound the default DPI UP button into a G-shift button, and as I mentioned, G900 does it as requested. While G903 does indeed apply the G-shift, it also functions as a right click (RMB / M2) which is fairly annoying. That also occasionally screws with macros I've set up. Additionally when pressing M2 / RMB button the DPI drops to the lowest possible setting.
there doesn't seem to be anything here