New heatsink design makes the fan run less = less salt creep in the fan blades. I have gen 2 now and am frequently clearing salt on the fan which makes a lot of noise. I also love the new optics with greater spread and color blending.
I went from a XR30 Gen1 to 2 Gen3 pros. Love the control-ability of these lights, but I can't upgrade from the Gen3 Pro to Gen4 Pro. So I'll need to replace my Gen3s.