OP, I was also considering using a Rock n' Play for DS starting now, but my concern was that he would get used to sleeping on an incline and wouldn't sleep as well flat on his back once he transitioned to the crib. Not sure if that's a valid concern or just something I made up in my head . I ended up getting the Arms Reach Cosleeper (mini) and so far so good. I have the Rock n' Play in the back of my mind though if DS ends up showing reflux issues at all.
DD 12/08
DS 1/14
We used it from the start. Ds2 slept in there until about 3.5 months when it seemed like he just wasn't comfortable in there. We cosleep now. I wish I had one when Ds1 was little, since we slept in the swing and developed torticollis. Ds2 has a lovely round head, but he was in the rock and play only for half of the night (then I moved him into bed with me,).
DD (3/06)
DS1 (7/09)
DS2 (8/13)
I have been doing the co sleeper, but the spit up problem seems to be happening again.....sopping wet hair, pools of puke, etc. Will move into the RNP tonight...
DD1 9 yrs old 12/2011
DD2 7 yrs old 01/2014