It's not worth losing friends over. Like you said, they love their babies just as much as you, it's just that they have had some awful advice.
Maybe just post a few links to your FB profile with little notes to say that you though it was really interesting or that you like reading new perspectives. I dare say that like all Mums they second guess themselves and worry about their parenting so being anything but gentle towards them will probably make them feel a bit defensive.