Hello SF, you wrote 2015/01/16 at 13:10:

I started the split scimitar discussion as a bit of a joke, but as noted, when SWA is on board, this is serious.

to extend this discussion a little:

http://en.wikipedia.org/wiki/Wingtip_device

look for "spiroid winglet" about 80% down the page (or use "search"
function of your browser). Could be more effective and less fragile than
the discussed Split Scimitar Winglets. I remember I saw some more simple
construction years ago (on pictures); those were a kind of ring-shaped
winglets. Maybe they are not as efective as the spiroids, but surely
more simple to build and perhaps not patented(?).