Its a stupid question.
You ditch a 320 into real water and you are going to have HUGE holes in it as it breaks up.
The Ditching pushbutton is really mislabeled. It should be the "Prepare for deicing push button" but that wouldn't sound glamorous.
The Ditching pushbutton won't change things by more than 1/100th of a second if the airlplane hits the water. The plane is either gonna float or it aint, and that will be more of a function of the fuel tanks than anything else.
Cheers
Wino