Just thought I would add regarding the heat situation...DS was born into a snowy UK winter and we carried him in the Close Carrier in the upright position and it kept him beautifully warm even in the snow! We just buttoned our winter coats over the carrier. So I am guessing that in an Australian winter or spring just the Close Carrier would be warm enough and swaddling on top of that might be too warm.
Also the reason we used the upright position instead of the newborn hammock position was because the fabric got all out of shape when we took the baby in and out too often and it would take ages to get it back to the right position. It is much easier to get them in and out of the upright position and they get more contact with you in that postion as well!