When I was in Korea, I got to try shine muscat and kyoho grapes. They usually have seeds, but by using giberellic acid on the flowers they are 95% seedless. Very expensive as it requires a lot of labor to keep the grapes seedless. Higher end grapes were selling about $25 a bunch. To get the fruits bigger, I have heard that they thin the grapes in the bunch. That is why I doubt that shine muscat will be grown in the US- it is not worth the cost of growing the grapes commercially.