We have a wanderer....and we bought the monkey backpack for him for Disney 2 years ago when he was 3. We brought it with us into the park, "just in case". Well...the boy pulled a disappearing act at dinner at the Crystal Palace, and from that point onward, he had his backpack on...even in the stroller. He's a bit of a "free spirit" and he isn't trying to be a pain, but he likes to explore. Funny story that happened on that trip...we were in the Epcot Character Connection, just myself and 3 of my kids. Josh was one of them...and he had his monkey on. I was holding the tail, and he was leeeeeeaning into it, just kind of hovering (as I hoped that it was stronger than it looked so he wouldn't face plant). The lady behind me looked at me and said "And to think I wondered why he had that on"..lol.
Yep...because I want him to have freedom, but I want to keep all of my hair, thanks. We are going back this year, and he'll be 5. The monkey is coming with us again...and I might have to get a Mickey one too...for our 2-almost-3 year old, since he inherited the wanderlust, as well.
I always explain it like this - if you were waist high or shorter, and had to have your arm hanging out above your head to hold a parent's hand, I would imagine it might get painful after awhile, and no wonder they try to twist out of the hold. I admit I was iffy about the tethers for years...made it through 3 kids before we gave in....but it does give you a bit of a peace of mind.
And let me just say....it's cool to see such a calm and rational discussion about something that can lead to arguments.