Quite apart from the fact, as Jay has pointed out, that autophoretic coating is not the same as powder coating, it's also important to remember that there are different types of powder coat.
Most people know powder coat as that horrible thick shiny stuff that does indeed flake off if the surface preparation and application is not perfect.
But other forms of powder coat are much more suitable for use on chassis. My new chassis (made by Terry Foxen) was powder coated with a much thinner semi-matt coating which is guaranteed for 15 years, it is the only coating that Terry recommends, and it's also approved by Kevin Vernon. Those guys know more about keeping Morgans on the road than I ever will, so I was very happy to go along with their advice.
And if I remember correctly Tim your chassis coating has a 'self healing' property, I would not be surprised that if you had a follow up coat on forward facing surfaces after 10 years that chassis wil outlast the pair of us! It's a beautiful finish, I remember having a good look when it was on the ramp the day you collected it, very impressed!
