early idle can lead to hard landing and maybe tailstrike.
In my experience, in tailwind, the 320 tends to sink on the runway during the flare. It is when you have a headwind that you can find yourself floating and floating down the TDZ. In a tailwind target speed is usually VLS plus five or even less.
Normally in tailwind landings I retard a bit later than usual because rate is typically higher and I don't feel I will arrest it quickly with pitch alone, so I fly the airplane with some thrust almost to touchdown, but I am not one of those who only retards after touchdown...