As Saprky said.
I remember when Al Rabe first wrote about this. His theory is that in certain parts of the pattern, the plane is in less than perfect conditions and the up line being in front would help maintain better control of the plane because it would have the most tension on it when it needed it.
Boy, that sounds confusing!
But he has his reasons that he spelled out.
I, too, have built planes both ways. I guess I am not up to the caliber of flyer that would recognise the benefits. Your milage may vary!