Kristoffer - we typically recommend blacks over whites for ponds because blacks seem to do better on a zooplankton/insect diet than whites. Whites seem to do better, especially at those 12 inch and longer sizes, when they have some fish prey. However, every time we generalize, we find exceptions, so that's probably why no one is making strong statements.
So, this really brings up the question of the fish community in that pond with 12 to 14 inch whites. I'd really like to know more about that one!