Wow, incredible! So those units have no way of deleting the files the recorder itself created? To me that seems like unbelievably bad, lazy, and shoddy design work. Could be just me, but it seems totally ridiculous that a manufacturer would say, hey, if you want to use our product, you'll need a pc handy to accomplish basic, necessary operating features that we failed to incorporate. That does take the wind out of my sails, but as you say, we shall see.
If M-Audio doesn't allow any way of deleting files off CF cards, maybe I could just bring along a digital camera to do the task. Not sure if that would work correctly, but I'd hate to need all those CF cards for a festival (if the OTG drive works for transfers), simply because there was no way to delete files or re-format.