In my airline that is now forbidden. Go figure...
In the case of a particular airplane being always "FAC heavier" it is obvious that the problem is in the FAC or the AOA probes. These will lead to longer float landings.
But in other cases where there is a significant ocassional difference between both PFDs and FMGC VLS, it is a good thing to add a few knots.
The reason in my airline for banning that practice is increased landing distances. We never land in any runway shorter than 3,500m.
Now I just adapt my flare to the circumstances: sharper with early lever retarding or more progressive with late lever retarding, according to circumstances.