I think that Bill mentioned something about a usb port for other controllers. Personally however, I really don't see the point. If I remember right, it's going to have a dual fightstick layout ( X2 joystick + 6 buttons ) and a trackball. That combo handles the great majority of games. Most of what it won't support are spinner based games (which are ok to leave out of something like this) and 3-4 player games (which could work.. sort of.. except there's no place to set the additional controllers, so they'd have to be hand held). Also, the more you'd use a different controller, the more I'd question why'd you'd bother to buy this cab because it seems to me you'd be better off just playing on a computer then
If AtGames has someone who knows what they're doing mapping the buttons, we're probably fine with a static button map. Also, if the cab is updatable, then they'd be able to fix it (usb update) if they blow the layout (unlike A1U). A game like Defender will always have issues on a control panel made for other games. However it shouldn't be too bad on this, because you should have in a 6 button grouping the fire/thrust on right, hyper + smartbomb in the middle, and reverse on left
My kids and their buddies are maxing out my Rampage 3 player cab every day and there's always a kid left out. This kid would gladly stand there with a control pad if it meant he could play rather than taking turns.