I researched this topic extensively 3 or 4 years ago, and decided to plant Yates and Prok (from Stark) grafted persimmons and Oikos seedlings. I only put in 1 each of the grafted ones, and they struggled a bit the first couple of years, but seem to have taken off this past summer. I pruned up a few to the bottom shoots this winter to try to get it growing a bit upright. Also, some of them may have been on the rootstock (can't remember for sure).
As for the Oikos seedlings, I have now planted about 50 or them and have them tubed. They are not all in the best locations, but seem to be surviving just fine. I seem to be getting the best growth in some of the areas with a higher water table. These have survived the first year which was one of the worst droughts of my lifetime (the have lumite at the base), and also 2 winters ago which reached -22 F for sure, but maybe even colder. I am now pretty confident they will work long term. I will keep planting a dozen or so a year and will someday graft them if need be. From everything I read, the earliest possible fruit with seedlings seems to be 6 or 7 years. In our MI climate, I'd be surprised to see fruit before 9 or 10. Here is on of the Oikos seedlings peeking out of a 5' tube at the beginning of growing season 3.