Gary Lager,
I doubt people add to their Vapp because they are worried about reaching stall speed.
I add to Vapp often and that's for other reasons.
Remember Vapp = VLS+5 (or 1/3 of headwind component)
And when I see a discrepency between the Fac computation and fmgc I will manually correct this.
The problem is, that a reduced gap between Vapp and VLS on the PFD is due to a slightly over estimated gross weight in the FAC computation and therefore an overestimated VLS on the PFD compared to the FMGC VLS which is more accurate. For that reason in light headwind you can increase the managed Vapp to avoid having a small gap between the two "values".
Correct you don't stall by going below VLS but on the day with a bit of turbulence at the wrong time being below your VLS and your AOA limit is being reached you will get Alpha Floor and you are now in the middle of a go around.
In fact I have been told by a technical management pilot in EZY that they recommend you to use a minimum speed of Vapp+5 until a new retrofit of FAC is introduced.