Dingoo-digital-usa deals directly with the people in china. If he says something, it has, in my humble opinion, much more weight, then all the other internet rumours, that are floating around. How should he give you any "proofs". For such stories there aren't any "proofs". All you can ask, is the source, that is telling the story is trustworthy or not?
And in my case, I think Dingoo-digital-usa is trustworthy, cause he is one of the two biggest Dingoo resellers outside china and he has direct contact to the manufacturers of the A320 and he is supporting the Dingooscene for quite a while now, with things like the HK Patchtes or with digging up obscure hardware documents, that help devs to understand the Dingoo better.
I don't really see any reason, why I shouldn't believe him.