Hi Tom,
Yes, I do have a King vine and have grown that one for many years. It ripens well here only in a good year, not on marginal years. This isn’t the best grape growing location. But it makes good juice when ripe. For fresh eating I like Marquette & Prairie Star better and definitely Bluebell (all seeded), though BB is as marginal to ripen as King. Here’s a link to my 2016 post on my grapes: Short Season Grapes. With 2017 update farther down.
King does get some black rot for me, though not as bad as Valiant used to. Plus it is a very vigorous vine and I have a small “vineyard” (6 plants). So I’m planning to replace it with a less vigorous plant. Though I love reading about all the wonderful table grapes folks are growing, for me it’s any grape that will ripen! Except for in situ grazing my grapes go for juice.