ForSerious
I think they have no plans of making this feature for the X series mice and Z series keyboards. Maybe if they make another series in the future. If you like GHub, stick with Logitech.
I would but they don't make an MMO mouse anymore. None of their other mice have enough buttons for me. The Evga X15 is perfect for me, not only does it have two buttons to the left of the left mouse button but it has an 'easy shift' button too for extra keybinds. The only other mouse to have that function is the aforementioned discontinued Logitech G600.
The EVGA X15 would be an up-to-date mouse with the feature I am looking for.
I guess that I will have to compromise somewhere. A shame, as a few years back I would not have needed to