I'm eating champadeks from my trees right now. I call them champs because they are a real champ of a fruit.
If seeds are from premium fruits you will probably get good fruits, although it may not be totally identical to mother plant, depending on who pollinated it.
They will get large, although not as monstrously large as a jackfruit, but they are much slower growing. They are much more delicate than jacks, especially at high elevations. And as Mike mentioned, there is a problem with a mysterious juvenille die off. So do baby them, especially at first. I suggest putting them in a wire cage with a light shade cloth, like 35% or 50% to protect them from bright sun till they get about a meter tall. Also give them a slow release fertilizer as they easiy get chlorotic. It's a good fruit and worth the extra hassle and long wait. I especially like how easy they are to open and eat. Not the messy mess and laborious cleaning project like with jackfruits.