>Assuming AM sees both spinner and trackball as mice, then in case I might like the option to try switching back and forth between the spinner and trackball on the fly (both active at the same time even better) for this purpose, could that be achieved by having the spinner set to the y-axis, and if so, what are the caveats of having it on y instead of x, with respect to game play in mame? (e.g. Would Arkanoid still play normally, etc.)If you have both a trackball AND a spinner you either need two iPacs (say an iPac and a mini-pac) or you have to assign your spinner to the Z axis. I don't think AM supports the Z axis for mouse input.
MAME's inputs are so configurable that there's really not a big caveat either way for actual gameplay.
If you connect multiple mice, Windows will let you use them all simultaneously as one "mouse". This is the case on my cab too, it has 3 trackballs. I can scroll the wheel from any of the 3 trackballs just fine. AM cannot currently differentiate them though, so I can't automatically rotate the display to where you're sitting (you have to touch the other controls for that). MAME, on the other hand, does know the difference, so two player games can work correctly.
> And lastly, would any of this negate the ability to simultaneously retain having a joystick up/down move one at a time?
Nope not at all.
> and I am okay with PgUp/PgDn, but would that require the i-pac to offer those keys?No conflict or special requirements there. The real PgDn key can be used, or not, it's fine either way. The hack just "virtually" presses PgDn/PgUp when you spin the ball very fast. I have my U-Hid programmed to hit PgUp/PgDn when I hold the Exit Game button ("Shift key") and press up and down on the joystick. But that has no impact for this spinner hack. Now that the ball is working so well I almost never touch the joystick now.
> I am not yet familiar with any of its mapping capabilities.
It's
really easy to change things around in the mapping software. I wouldn't stress out about it too much.