Electrical guy here!

I DO like the idea, since at the moment I walk down to the garage with a fistful of USB drives to experiment with different settings. Being able to switch between two would be nice.

I was thinking: Once the config file is uploaded, there's no need for the ALP to "see" it connected anymore. Hence, no need to latch the toggle (ON/OFF/ON) to that particular device. You could make that toggle momentary... but then you'd have to keep it held there until the ALP is done loading.

I'm assuming you're thinking of soldering in a toggle for pure simplicity? As in, "toggle THAT way for PDC. Toggle the OTHER way for ___"? Otherwise, the USB hub you linked would work just fine as-is... as long as you can keep track of what switch you've pressed.