Wow! This is a very interesting piece. I've co-slept with all four of my babies. I nursed them exclusively (none of them have ever had a bottle -- straight from breast to sippy cup) and never felt they were in danger of becoming smothered. Of course, I don't think I ever fully went into R.E.M. sleep the entire time they were infants and sleeping in my bed with me.
I didn't have a good relationship with their father and he wasn't often in the bed with us (just about enough to produce 4 babies!). I've since divorced and remarried, but was still nursing my youngest (far too long according to some people) when I met my soulmate and Dragonslayer (Duane and the wonderful, amazing stepfather of my kids).
Our new and delicious intimate relationship made co-sleeping impossible, so little Sarah had to "go it alone". ;-) Anyway, I loved loved loved co-sleeping and feel a bit sad that my own children (especially my daughter) may not co-sleep with their infants due to these studies and educated medical opinions.