I feel like that depends on how much the small deck can really benefit from extra filtering and whether the larger deck is creating great enough returns on creating a better odds.
For instance, redcoats + DBS could avoid agenda flood in the beginning of the game while finding agendas later. Hitting R&D is already hard, but if you made the deck bigger (and were able to consistently get DBS) hitting R&D would be almost pointless (and HQ by proxy) because agenda density would be lower for the bigger deck and greater number of 3 pointers while also maintaining a low level of agenda points in HQ.
I don't know. My long time in card games is telling me this idea is bad because you have to find DBS. But then I look at an ability like NEH's which effectively decreases deck size anyway and I'm feeling less bad about making the deck bigger, and then I'm left wondering if even though it might mean a slower game win percentages might go up in other decks with such a strategy. Basically, you only get agendas when you need to and the runner has a hard time finding the ones that are valuable to you which makes it less likely they'll interrupt your plans.
(And then anecdotal experience playing with DBS is reinforcing this hypothesis that I feel like I should know is bad; but the scientist is saying that the experiments are opening up a hole in my world view).