VREF means Vls when in config FULL. i.e. Vs + 30% margin. (1.23 x Vs1g in Airbus speak).
Therefore if you did a flap full landing your margin over Vls would be zero if you didn't add any approach correction.
The same applies for abnormal configs i.e.
Vls = Vs(current config) + 30% which happens to be VREF + 25kts for G+Y failure.
So you only have a margin over it if you need to add an approach correction or decide to increase your Vapp speed for turbulence etc.
At our lot, we always add at least 5kts and never fly Vls, even if using manual thrust due to risk of tailstrike.
Hope that helps (and is correct, it's late).