@ChipToothy - YMMV with either method. From my own experience, neither Plastidip nor spray paint hold up very well against the elements. They all seem to chip, crack, and peel over time, but look great when new as you noted.
If you're going to spray paint plastic fairings, make sure you use a spray paint that is flexible and designed for plastics. Plastics flex therefore so must the paint. Krylon makes a fabric spray paint (you can find it at auto and dept. stores) that does pretty well on plastic because it's flexible. If you wipe down the plastic surface well with 91% Iso alcohol before you spray, and maybe do a little sanding, you will usually get better results.
On metal I've had good luck with this stuff -
https://www.krylon.com/products/supe...tallic-finish/ ...I used it to re-paint my Hawk's front forks (which were marred a bit from shipping) and they turned out great. The paint has held up well so far and looks as good as the original paint.