unfortunately they are equally astringent until ripe. There are a few hybrids of american and asian persimmons on the market but even the hybrids are astringent until ripe. However with a renewed interest in native edibles like persimmons and pawpaws gaining back popularity it wouldn't surprise me if a non astringent american hybrid is one day available. maybe even interspecific hybrids of black sapote and persimmon may be possible. Right now most non astringent persimmons are grown commercially in zone 8 and up but there are some homeowners who have successfully grown them in zone 6b via microclimates. A non astringent american hybrid that can be grown commercially as far as zone 6 would be a huge game changer and open new markets for colder climate farmers.
