ad319, you make me laugh. Your saving is probably correct at LGW where you are instructed to slow down to 160 at 10nm and maintain it to 4. But there is life outside Gatwick...
I am based at RAK and each time 28 (25km vis and clear sky) is in use, almost all the orange guys fly a full IFR procedure, followed by a circle to land with gear down and F3 instead of a, straight forward, visual approach. Did you save 9kg or did you just waste 491 kg?
When I flew the airbus I saw people configuring ealier on a F3 landing, reducing the benefit to almost zero. You only save the fuel if you accept that your approach will be stable 100-200ft lower than on a F full landing.