I'm considering getting the njoy bubble for dc3 (due at christmas). Has anyone used a "lie-flat" stroller from birth, do they actually work? I've used pram/slings for ds1 & ds2, but the pram has now broken and I don't really want to buy a whole new one. I will use the sling alot, but I like to have something to put them in too. I'm worried the baby won't be very comfortable using the pushchair straps etc....