Many of those poor doing seedlings I just planted inside a group pen and have done little since. On the site with poorer soil they are just fading away, except for three or four trees that are doing very well. On the better soil, about 3/4 of the seedlings are doing better and I give them slightly more care.
That is why I say, if you go the seedling route, just throw out the slow growers. Expect a few to not have the winter hardiness of their parents and expect a variation in CAR resistance. Survival of the fittest and not much different than what I got by buying from a Michigan wildlife nursery. Actually my hardiness survival is a bit better, as my seed source is from the north. My apple size is just as good as his varieties=variable.