What are the chances that a Kerr seedling will make a standard Kerr apple?
I planted a couple dozen red splendor crabapple seedlings and their fruit is all over the map. Some are the standard 3/8" red fruits that I was looking for and some are 1" yellow crabapples. The rest fall somewhere in between. I would expect to see quite a bit of variance in Kerr seedlings as well, but who knows.
I think seedling trees are fine if any old apple will do, but if you are looking for a specific type of apple then a grafted tree is the way to go.