I use a beco Butterfly II, which is very similar to the Ergo. I love it!!! My son is now 14 months old and 20lbs and I still wear him when we go out. It is so much easier, we went black friday shopping and he wouldn't nap in the stoller, so I put him on and he was out in two minutes, he slept for about an hour. I havn't really worn him on my back yet, but the few times I have put him on the back he has done fine. He loves to go on my back in the mai tai but I don't care for it becasue he spends the whole time playing (pulling) my hair! But somedays it is the only way I can get stuff done. I only use the mei tai in the house because I also find the straps a pain to use when I am out. I also use a ring sling a lot, especially for quick in and out trips. If I were planning a trip to WDW I would probally bring both my beco and my ring sling and switch back and forth depending on what we were doing. I know I took both with us on Black Friday but I ended up only using the Beco.