A320 will never be approach climb gradient limited in config2 overweight G/A.
But 321 sometimes will and therefore require 1+F for go-around.
To keep it on the safe side, Airbus made 1+F overweight go-around procedure mandatory across entire rage of its narrowbodies.
Source: my training manual.
It's a bit unnerving to move flaps from 3 to 1 and suddenly see Vls move above your current speed but, with both donkeys alive and kicking, you quickly get above it (at least in the sim).