Hi,
A little while ago ( if your a senior), or about 25 years if your not , RCM. ran regular articles on small aircraft. In one article on 1/2 A pylon racing they were discussing the merits of low drag wing tips. one had a streamlined (rounded)leading edge wingtip back to wing max camber (about 30 % or so) and then straight back to the trailing edge. they experimented by making up a wingtip and installing it on a aircraft with squared wingtips, they flew the model and they found it yawed to the square wingtip . so i guess that shows if you have the right streamlined tip you reduce drag and increase efficient
Earl.