Once the initial setup is done, the parts owners keep coming back to are the button layout and the feel of the mouse itself. People build out per-app or per-game button schemes, some borrowed from years of habit on older mice, and the weight of the MX Master 4 gets called out as comfortable for long sessions.
What becomes routine, less happily, is checking in on the companion software. A macOS certificate problem surfaces repeatedly: the app gets stuck loading, custom buttons stop working, or scrolling inverts, and owners have had to learn where to find Logitech's patch page or apply a manual fix. Several say they've had to redo this more than once as the issue has resurfaced with later macOS or Options+ updates.