I know your familiar with the Dexter shoe separation problem I had recently.
Dexter stood by their product and refunded my cost for the new shoes.
POI..although the lining is considerably thinner than a comparable auto shoe, Dexter insists their replacements are made in the USA, not so much for the on-line loaded assemblies that are available. (according to them)
We recently used the trailer for the first time since the repair. I did not arc the shoes and was anticipating some adjustment problems. Negative. Did notice one drum running 20 degrees hotter but re-adjusting took care of that. I also like the simplicity/reliability of the trailer drum brake system, willing to give up some efficiency for reliability.
A few years back I was considering the disk up-grade but after some research here decided to wait. When AS stopped offering them I thought that was a prudent decision.
I can appreciate your frustration in getting your system working properly. But I think if you get the drums and replacement shoes matched up, along with good magnets and clean, smooth plates everything should work properly.
Keep us posted...