The A320-100 has no wing tip fence, just a kuchemann tip. The A320-200 came slightly later with a WTF. Don't think there is a A320-300.
The photo you have there is a large winglet programme, fitted for flight test, but dropped due to (as you say) the requirement to make the wing significantly stronger.
No I'm not a geek, but an aerodynamicist for a large european aircraft manufacturer.
I want to be a pilot though.