Thanks to all for the information on winglets and lift production in general.
It seems there is still a lot to be learned in design of airfoils, even NASA cant give a defintive, simple explanation of what produces lift, in what amount the sucking or deflecting proportions are.
The hours of research available from some of your suggested links has left me with bleeding eyes and a sore back, for those who want the simple version, my reading of it is-

Wings produce lift by diverting air down. The reactive force is up, the balance is drag.
Winglets enhance the lift produced from the wing by minimising vortices (drag) produced where the upper and lower airflow mixes at the wing end. The balance again is drag, it wouldnt matter if they were up or down facing, for the purpose of aerodynamics.

I particularly liked the spoon-in-waterflow demonstration (so did my kids) and recommend everyone tries it.

Boom time here in oz, 1000k flights, competitions, sun, sun, sun.

Wayne