I've never seen the Stebel unit, but electronic cathodic rust prevention stuff seems to work quite well in water-emersed and/or earth-connected structures. That said, these devices are nto as popular in the automotive world and several tests document that some of these can either be snake-oil or not well suited to the multiple individual metal bodies often found in the automotive world. Larger bodies of well-connected non-endged metal are often "best suited" for cathodic protection (electronic or otherwise). To me, it seems that the motorcycle, by nature, has limited amounts of large and un-edged metal areas...
The imposition of high frequency on what would otherwise be a DC process is an attempt to increase the area of influence/penetration for non-circuited voltage flow. Often this can be done by actively tuning the operating frequency to cause the conductive metal to resonate a bit, but I'd question the efficacy of a one-frequency fits all application
For my part, I'll wait until one of the manufacturers post a bond to replace anything that rusts while their equipment is connected.
Of course, I'm not short of opinions. I'm sure that some good research will help to form some solid thoughts that may or may not align with my personal biases here. (for a boat or bridge - hell yes! cathodic protection using sacrifical anodes or electronics is proven; for small bendy partially insulated metal bits driven about on roads, I'll pass)