I think the number and type of admin buttons depends upon who will be using the cab. If you've got enthusiastic non-tech saavy friends or family, then remove all the admin buttons. Just use P1 start button to start a game and put the Escape/Exit game button off the panel, maybe right above the coin door on the underside of the CP would be optimal, so anyone can easily reach down and hit the button to get out of a game, but it will never be accidentally pressed.
If, like me, the operator is going to be you, then you might want want to add some gameplay enhancing buttons, such as pause, save (state), load (state), and actually the admin button that I use most is Rewind because it's better for learning those gotcha moments in many arcade games.
I use Hyperspin FE and I really don't like the Hyperspin button. If you are the sole operator, you can map the genre and favorites buttons to P1 action buttons, but I have my system starting in the favorites list, so I don't use the favorites button much. The genre button can be nice if you have separate favorites lists for 3 and 4 players or trackball games, 4 way games, etc. I have the right and left navigation buttons for searching by letter mapped to P1 action buttons 1 and 3 because Hyperspin would frequently crap out when I would hit diagonals navigating with the joystick.
Again, if the cab is going to be operated by others or you just want a more authentic arcade experience, I recommend no admin buttons, just boot into a curated favorites list, start with P1 start and exit button off the panel.
P.S. If you have enthusiastic trackball rollers, they are going to hate that 4-way joystick. They'll probably punch your screen rolling that trackball in World Class Bowling or Golden Tee, too, so hopefully the screen has a protective glass or plexiglass in front of it.