I built my 3D planes ,all 2 of them with big tips. (long) The reason, is so when pattern style flying it helps with reducing the giant alerons effectiveness. 3D alierons are so big that when trying to fly fast the are very responsive. To responsive. When in a hover the prop blast is only covering say 30 % of the wing so Paul is correct in the fact that they dont make any differance at all in controllability. And when fun flying they dont create any advantage. Only when flying fast will tips help so if your trying to get all ranges of peformance i would recomend them.

Dave G