A320 OP DES at low altitude

[Giggey]

Hi All.
As by subject i was once told that using Op Des at low altitude was not a great idea because it could have taken into some unmanaged V/s ratio and maybe activate some gpws warning and to use V/s instead which i have to say i agree pretty much.

I am now trying to find some published reference to this theory but cannot find anything either on fcom 3, qrh nor Fctm.

Any clue if that might be just some company policy or it has an origin from Airbus?

thank you.

cheers