I've been playing with it a little here lately. Pretty cool stuff.
I did my heel guards and my center piece on my chin fairing, both susceptible to rubbing and catching debris. Both have surprisingly held up decently. I have no chips in my fairing after about 100 miles. I have some marks on my heel guards from my boots rubbing, but nothing that has ripped the plastidip away from the guard.
Having said that, my guess on something like just doing an airbox/zipper protector may be more trouble than it's worth. Reason is, if you zipper catches that and rips it, there is some time involved in re-doing it every time. For something like that, I might just spend the $20 and get a real protector. BUT it would be fun to try out, play with some different designs, and see how it holds up. I just don't forsee that being a long term solution.
fyi, i just purchased some black heel guards because I know the plastidip won't last forever and I like the look of them being black. So if anything, try some different colors and see how it looks.
and post some pics! up]