As far as I know, the oem rack is the only one that doesn't require drilling through the fender. If you are wanting to strap a bag down or even mount a luggage case you are going to want a rack. I am biased of course in opinions about racks because I make the Jscaggs Racks and I have no doubt in my mind they are the best solution. If you are worried about damaging the oem fender, rest assured that replacements are only about $25. If you felt like you are concerned about drilling the fender correctly send it to me and I'll do it for free. I make a BIG Rack that you can mount Givi monokey cases directly to, and the Slim Rack which is more sleek. Both are ready for Rotopax as well.
Jared