My old Logi G500 has 2 features that I miss compared to my MX master 3.
1. On board memory to store settings. When Options+ isn't working properly, my MX's button mapping resets to default settings. If it saved it all on board, this wouldn't be an issue.
2. The scroll wheel on the G500 had left and right button clicks. I just assumed the MX 3 would have this but it doesn't and I miss it a lot! I used it for navigational gestures on MacOS. It was much more intuitive than pressing a button and then swiping the mouse to perform the gesture Would love to see that feature added back in.