A few comments.
Tron is not an analog game. I believe it is actually a 4-way game. (Or to be more exact, the software is 4-way, but the sticks are 8-way but with very tiny diagonal areas).
2 trackballs just so you can play dual marble madness, but no 4-way at all? (There goes about 180 unique titles).
Puchi Carat is a 2 player simultaneous spinner game, and there are others as well.
With two trackballs, 4 primary joysticks, 2 seconday joysticks, 1 trigger stick, and a spinner, there is no way that anyone will be able to walk up and play without your assistance anyway.
Guys can USUALLY figure out where the player one position is, but I can't tell you how many of them will start bashing on the first button in the second row of buttons and wondering why it isn't shooting. As for girls? Just forget about it. Girls tend to gravitate towards the most eye catching control on the panel, no matter what the game. If that means trackball for Pac-Man, light gun for street fighter, or one hand on each stick for Arkanoid, then so be it.
I used to have a panel with 2 eight ways, one 4-way, trackball, and spinner, and far too many people went for the wrong controls. Later I had a cabinet with a single player layout that had one 4way, one 8-way, and one trackball that all shared a single bank of buttons. That one was even worse. Most people had trouble with it.
Finally I went with what I have now. A vertical cabinet with a single 4-way and 2 buttons. Along with a horizontal cabinet with two 8ways and six buttons each. The only problems unassisted friends have now is the one about thinking the fire button is the first one in the second row. Oh, and some people get confused because the horizontal cabinet takes quarters (or you have to trip the coin switches at least), and the vertical cabinet coins up with player2 start. I may just have to wire the coin switch on the vertical cabinet too, just to keep things consistant.
I am probably going to toss together a trackball only cabinet for a third machine. I know the control panel is just going to cry out for some other kind of control (analog stick, or spinner, since I don't have either anymore), but I am going to resist, since extra controls confuse people.
I think I got way off track here. But basically. Real arcade games did not have extra controls (except for unused buttons, which were common in conversion games), and extra controls tend to confuse people.