As most Amel owners know, painting aluminum is at best still a risky issue. Many A55 owners know this better than previous Amels. I am not sure why there seem to be more aluminum coating failures lately, but I suspect it has to do with certain prep chemicals being outlawed.
We had an AB aluminum dinghy for 11 years. When it was 10 years old there was less painted area than bare aluminum. I thought Highfield and sister company 3D offered dinghies that were electrostatic-spray powder-coated. I would assume that this painting method would be better but it might make the process even more difficult and thus risky to the coating losing adhesion to the surface.
Whatever the issue is with yours, why don't you give the details, but focus on the aluminum coating issues rather than the manufacturer because I believe that probably any manufacturer and possibly any Amel owner will experience this issue.
You experienced coating failure with Highfield and I did with AB Navico. Today AB ships the aluminum dinghy uncoated. You can special order power coating. Their website states, "Although the tender is uncoated for minimal maintenance, you can choose to add a Chrome-free Pretreatment and Powder Coating." Another brand that I like is Caribe. They had the same coating flaking problem that you and I experienced. They solved it by no longer offering aluminum hulls.
I believe that there is a risk of coating failure with any aluminum dinghy. I think you are lucky if you do not experience it.