The 0-3 month size was our favourite, larger size less great
We were given a 0-3 month ergo cocoon as a gift and it quickly became our favourite swaddle. My husband would do a load of laundry to get it clean rather than use one of our others. It's easy to put on, and a nice thickness. Our babe was perfectly warm and comfy with just a sleeper underneath. I found the sleep sacks with the big wrap panels that Velcroed around (halo) made him too hot with all those layers. Our little guy isn't very little, so he outgrew it before long, and we bought two more of the bigger size. We weren't quite as crazy about those, as they weren't as snug through the chest, so they didn't have that tightly wrapped effect. He started soothing with his fingers and thumbs though so we just use them as sleep sacks with arms out. Only complaint there is that he's a chubby guy and the arm holes are about as tight as they could be without being too tight.
(Posted on 4/3/14)