You are probably hamstringing yourself with your criteria.

The kind of study you describe is almost impossible to conduct, due to ethical considerations and the difficulty of eliminating confounding factors. A more useful and valid way to look at breastfeeding is to try and examine very specific outcomes, which is why you'll see most of the studies are geared that way. But just because they're not randomised, double-blind trials shouldn't automatically exclude them from consideration.
You're absolutely right, and I'll definitely continue looking at the type of material you're suggesting. But what I am generally getting at is that some of the very substantial claims made about BF'ing must be backed by some stringent long ranging studies, surely?

I know you don't want a debate and that is fine but as a breastfeeding mother I find this comment offensive. I may not have researched my decision to breastfeed over formulae feed because for me formulae feeding wasn't even something I wanted to consider. To me breastfeeding is free and natural and therefore my first option and I have been lucky that I am able to feed for as long as I have. I understand in the case of twins where the physical and mental toll is greater why you would want to look into the pro's and con's further but I am offended at your implication that I decided to breastfeed wasn't based on empirical evidence and therefore I am somehow uneducated or doing the wrong thing or uninformed?!
That is absolutely not what I said or implied. I asked a direct question without making any inference or comment about anyones personal choices, and specifically avoided getting into all this touchy feely sensitive hoohaa, so I have no intention of derailing my thread with your problem.