Yours is a very good policy, Pete:
IMO, the standard policy should be that before you start trading and selling, you should have grown the cultivar and produced at least 1 harvest, with photos to confirm the named cultivar. Several forum members have done this simple procedure for years without DNA testing or excessive guarantees.
Your policy is surely one of the best ways to go.
That said, it might be worth pointing out that I was able to get a lot of good cuttings to people, including quite a number free cuttings, last year which wouldn't have happened had I strictly followed such a policy. For example, the first problem order I looked at was as follows: I sold 2 Mary Lane, 2 Negronne, 3 Brooklyn White cuttings in a single order, and gifted free on top a cutting each of Hunt, Keddie, and Janice. I had grown and ripened and eaten very good fruit from all those trees - the Hunt, the Keddie, the Janice, the Negronne -- except for the Mary Lane (from a tree from a reputable nursery) and the Brooklyn White. In my opinion, the customer got a good deal despite my mistake. But we'll see what the customer thinks, might be completely different from what I think, and I do think now that I did not know enough about the nature and origins of that Brooklyn White to sell it with the confidence I want to have. I've just now gone ahead and reached out to that customer since that person turned out to be readily reachable by email.
Thanks for the suggestion and link.