All theory aside, an A320 will tend to float with any kind of tailwind. Hardly any flare is needed with a max TW. If you flare, you'll float.
F3 or Full? Personally I will only consider F3 in the most benign tailwind conditions, i.e. stable tailwind, no thermals, exactly on profile. If you get high on profile with a tailwind and F3, you WILL loose speed control. Same with thermals, your speed will run away with the engines at idle all the way down, especially in the A319.