Interesting thread. I had 4 children (no twins) within 8 years and breastfed them all up to around 7 months. The whole "breast is best" ideology was definitely prevalent in all the ante and post natal care I received, though the main benefit propounded was more about the antibodies in breastmilk that are not replicated in formula. Not so much about attachment.
I was never one for following parenting guides so I breastfed on demand, hourly if necessary in the early months, and never really tried to impose a rigid sleep-routine or let any if our babies "cry it out." There are definitely pros and cons with this approach.
As a breastfeeding mum you are instsntky and necessarily cast into the role of "default carer." As soon as the baby cried, DH's reflex reaction would be to bring him / her to me. People used to always be telling me, "Tell him (DH) to get up and help you on the night", etc. but as I never really could manage to express milk, what would have been the point of him also existing on a broken sleep pattern? It also meant that I became accustomed to not being able to go out without the baby for more than a couple of hours at a time - it was a feeling of being perpetually rushed or like being on a piece of elastic pulling me back to the house. This feeling has never fully disappeared for me somehow. Even when I was out with the baby I was always anticipating the next feed and where I would be able to do this. Basically, as a breastfeeding mum, the health and survival of the baby is down to you and your milk alone and there is not a lot the DH or anyone else can do about this.
I do sometimes wonder if mine DH's parenting roles would have developed along more equal lines if I had bottle-fed. As it is, I've not returned to work since having DC (eldest is now 13). The mindset of default carer has stuck, for DH as well as for me.
I could never be bothered with parenting books, etc. I just did what came most naturally to me at the time. I think the most important feminist aspect of feeding babies is choice. If I recall rightly (it's been many years since I read about Bowlby and attachment theory), the central concept to this is the "good enough parent" - ie. one that is adequately responsive and consistent towards the infant. There is no reason whstsoever why a bottle-fed baby should be any less attached to the mother, as long as the caregiving is consistent. There really is no right and wrong here. I was bottle fed myself because that was the trend at that time.