So not to be a Debbie Downer, but a friend of mine has the FP rock n play sleeper. At her LO's 8 week appt the doctor noticed a serious flat spot already forming on one side of his head. The doctor specifically asked my friend if they use this sleeper because this isnt the first case she's seen. Fortunately, they had been using the RNP only about 2 hours each day, so the flat spot wasn't as serious as it could have been. Her son has to go to physical therapy to help his neck muscles and they're hoping he won't have to be in a helmet. To see if this has happened to others, we looked up the RNP on amazon. We found several reviews from parents whose LOs slept in RNPs for most of the night for weeks or months, and their little ones were diagnosed with torticollis and flat heads caused by the hard, angled headrests on the RNP sleeper. Many have to go to therapy and are in helmets, and some are even seeing plastic surgeons.
I see a lot of people talking about the RNP on this site, so I just wanted to warn you to at least keep an eye your LOs positioning in the sleeper and check their little heads often. If I had this sleeper, I would throw it away.