Anybody try the Ergo? I have a Maya wrap right now, but DS is getting big enough (he's only 14 lbs or so, but still) to make it uncomfortable for my shoulder. I need something that distributes the weight evenly on both sides, not just the one shoulder. We like to carry him in front, but we want to start carrying him on our backs when he's ready so we can wear him in the kitchen and on hikes. What do you think about the Ergo or any other carrier you can use as a back pack (we don't want a big framed back pack though)?