My Cara-Cara is on its third year in ground and finally looks like it will hold its first fruit. It always flowers good and holds fruit a while but drops them. Kishu on the other hand really holds a ton. Fukushu is my only kumquat variety that seems to wait it’s sweet time to fruit, also third year in ground and yet to fruit. The nagami, marumi and meiwa all fruited first and every year since. Maybe the Fukushu will this year, just saying my experience with some of the varieties you mentioned.