So the breast feeding pumps do not work for breast growth. You might get a spike in prolactine levels caused by the nipple stimulation which could enlarge your breasts temporarily but it would be small and not permanent. The full domes that cover the entire breast do work well. The principle is very simple, tissue is stimulated to grow under negative pressure. Well documented by the medical industry. So every time you pump your breast tissue expands and the negative pressure causes a little bit of growth. The more you pump the more you grow. it is all about exposure hours. And breast pumping does not change any of your hormones.
As far as beneficial? That's totally up to you whether you want larger breasts or not. For me now that I am a 36D, it make my bras fit nicer and make my dresses look better.
Hope that helps.