For the Do it your selfers here, the following.
I've had a few things powder coated in the past working on boats, but found it does not work well is salt air environments.
I live next to the Atlantic Ocean in a place where we get salt and sand on the roads 7-8 months a year. My bikes take a beating.
In 2015 I bought a 91 in England, rode it for 8 months then sold it when the ship left with the caveat that I kept the rear rim. It was in tough shape after a winter on the roads. When it arrived back in Maine I had a think and decided to try painting it myself. I sanded, taped and cleaned it with alcohol, the applied 3 coats of this.
Specialty Appliance Epoxy Spray Product Page (rustoleum.com)
Ran it for a year and decided to paint my front rim (had a third gen front in white but wanted to keep the floating rotors on my 97.)
Since 2016 I've put around 40K on the bike, have touched up the rims occasionally when putting on tires, but that's it.
For me the benefits are.
1. I do not have to ship my rim and worry that the sandblasting will damage the bearing/bead surfaces or the tire stem.
2. The cost is about $15 for paint, tape, and alcohol.
3. Most importantly, I can repair/touch up the rim myself, which really is not possible with powder coating unless you strip the rim.
Just my 02 cents and Humble Opinion.
FWIW, its says Epoxy on the front label, l but is really an Enamel when you look at the specs and on the back of the can. No idea why they do this, but enamel is far easier to work with and repair.
My 4th Gen has the Rustoleum on the rims, my 86 and 90 are OEM. I can't really tell any difference.