Eric,
I don't plan on having a trackball... I just don't see being able to play doom worth the extra hundred bucks

Anyone who puts doom on their cabs, I would suggest getting the Legacy port of the doom source code. It enables 2 player split screen DM on 1 computer, which would probably be fun on a cabinet.
Just a matter of getting the controls set up comfortably...
Shoot, open, the four directions on the joystick, with 2 strafe buttons, and you're good to go I would think.
If nothign else, it's just another degree of novelty.