I think we should treat all kickoffs as first onside, then normal. If you start in the onside mode and the kick is long, you have a few seconds to adjust to the normal running play, but if you start in the normal mode and the kick is onside, you don't have any time to adjust.
Granted, with 4-5 officials, covering an onside kick from the normal positions is tough, but that's what we have to live with.