Oh. I missed the right stick, thinking the top-fire above the buttons was it. Okay, then....hmmm....well, I'd definitley like said above, I'd not put any bottons in line with the trackball. (Now, it must either be spas-ism or just drunken-ness....or both... that makes people do what lew says.) As for the top-fire, I don't like to reach that far up the panel* for anything in-game, but if you like it....
Also, there's gotta be some room for mouse buttons without seeming crowded as you have them. And for a composite CP, I like the standard arrangement, cos I can set the controls so my wrist is straight - for example: in single-player games, I use the left stick and the right buttons. (This means I'm not leaning over the panel/maintain good posture. It would be neat to have a batch file for 2-player simul games that would set the controls, thusly, if you only press 'player 1'.) A more specific example - Asteriods: I use a stick for turning, and I use the following buttons of 'player 2': top-middle, fire ; bottom-left, thrust ; bottom right, hyperspace (or, Ast-del, shields)...that is, an arrow formation. You could still do this, but as well.
*See panel image.