I thought marumi was listed as being not true from seed?
Also, more dwarfing than FD would be a big surprise to me... do you have any links or books you can point me to with more information about this?
I have a fruiting marumi right now I have been eating fruit from for weeks. It appears nearly identical to Fukushu, btw, except that Fukushu has a more pronounced "finger dimple" at the bottom of the fruit, and I've read fukushu is true to seed while marumi is not.