The USB footswitches are independent of the keyboard, they can be viewed as adding a mini keyboard to your computer. The normal switches that plug into the Advantage keyboard can be viewed as extra switches on the keyboard itself. I am using the latter and have both a kinesis footswitch, as well as some generic ones that I wired to an RJ plug. Since you are on OSX I would suggest getting the normal Kinesis footswitches (not the USB ones) since the regular ones can be programmed from the keyboard itself, just like all other keys on the keyboard, so it's completely OS independent. You can have up to 3 pedals hooked up to your keyboard, for different actions.