Persimmons are fairly healthy trees. The only things that have attacked mine are grasshoppers and our cows when my DH forgets to close the gate. You will have competition with birds and wasps for the ripe fruit, but the trees are relatively short so it is possible to cover them or remove the fruit when they are hard ripe and let them continue to soften indoors.
Using the D. virginiana as a root stock will mean that the grafted Japanese persimmon will be susceptible to Cephalosporium wilt which will kill the tree. You may want to contact your local cooperative extension service agent to find out if Cephalosporium wilt is found in your area and what the likelyhood that it will move into your area is before you purchase your persimmons. You may have to compromise and sacrifice a few branches to freezing weather now and then rather than a whole tree to Cephalosporium wilt.
I've got to go take care of a few things, but will return with a few more comments.
