You can order the trackball with or without it's own usb controller, and you can run it off the ipac uio, but it does take several inputs away from the ipac. Using the u360's means you can free up 4 inputs each on the uio and still have enough room to run a full 4 player setup off one controller. It is true, if the ipac uio had just a few more inputs and outputs, it would be even more perfect for a full 4 player "frankenpanel". Since my trackball and mouse cover the p3 and p4 joystick inputs, I used the p1 and p2 for p3 and p4 and used the u360's as joysticks through their own usb. I could have freed up tons more inputs on the ipac too, if I had chosen to us the u360 inputs for the buttons. But in the end, if you are going 100% switch based controls and also want to use a spinner and a trackball, you will have to add some other form of controller.