The answer depends on what a Little is comfortable wearing, how much protection they need and what sort of protection we're talking about.
In our opinion, the feeling of a pad is different enough from a diaper that we would not consider a pad to be sufficient enough. They do not suit our biological needs, and only under certain circumstances we wear them.
As a side note, we use pads to better our diaper usage economy. See CUT THEM DOLLARS ON THEM PRICEY DIAPERS BY USING OVERNIGHT PAD. In short, we lay a pad in our diaper and swap that out as it's used, prolonging the usability of any standard diaper while reducing the risk of odors and rashes.
The goal of regression is to find comfort in your environment to better express the Little in you. We like the thought of wearing diapers because we're then wearing a garment designed to suit our needs Adult Babies, they feel comfortable, familiar, and they are aesthetically printed to align with our visual preferences. If pads contribute and target to the particular feeling of comfort you're seeking, we don't see why you couldn't or shouldn't wear them.