A 1% fuel penalty would be significant over the course of a year, especially at todays fuel prices! I suspect one of the reasons the winglets are smaller on the small Airbusses is that the wings tend to be optimised for where the aircraft will spend most of it's time. An A330 will spend a lot of time in the cruise, hence if a winglet can reduce burn in the cruise it's worth a lot. A short range aircraft like an A319 will be up and down all day long with the wing optimised for that regime. I had heard that the winglets were originally added to the 320 series to reduce wing flutter. One must also consider that while the 330 winglets look much bigger then the 320, the 330 also has a much bigger wing so the proportionate effects could be much the same.