I don't know if Longans will grow true from seed, but even if they didn't, they will still be good. And with 25 trees, one of them is bound to be a great one. You can always graft a known variety, such as Kohala, on your other 24 trees if you don't like them. Or maybe I'll start a bonsai forest of Longan trees. So many ideas! Most likely though, I will end up giving these away.
I dug the seeds up after a week, and this is what they looked like: