Not sure if this helps but the 777 was built to compete for the dc-10 routes and therefore the gates as well (as we all know), but the 777 was also designed with an optional folding wing tip to fit it into small gates...no airlines have to date ordered this option but it may lead to the winglet problem. Also it is my understanding that winglets are utilized to benifit the a/c's range capability. 747 = 3% more range with added winglets, since the 777 is designed for medium range and has more than the capability in its fuel tanks to meet the design requirements the winglets again are possibly ommited here????? All theoretical......