Just because they're small doesn't necessarily mean they're not healthy. Granted, a lot of little ones seem to get sick more, and there's a whole lot more precautions to worry about... getting stepped on, jumping off furniture, REALLY fragile, but I know there's a few on YT with little ones smaller than 4lbs so hopefully they see this thread
I would be a wreck. I am very content with my 12lb boy and wouldn't want it any other way! He seems so small to me so a 4lber... I just couldn't do it.