I think you are meaning SNS (supplimental Nursing Systems). I have known Amoms who have used them both with formula and expressed Breast milk. I think they are a wonderful alternative for a mom who chooses not to take medication to induce lactation.
They are great in fostering the bond between mother and baby.
I have also known of moms who used them when they have not had enough of a milk supply. Either way, taking a baby to breast is one of the most natural things. I am not against bottle feeding, but if you can breast feed of supplimental breast feed I say go for it, if only for a little while. It is such a wonderful bonding experience. I know I sound repetitive but I am a big advocate of BFing whenever possible both for bonding and the values of breastmilk..
Try it, if anything you can always go to bottles if it don't work out.
Medela Supplemental Nursing System (SNS)
EZ