The Baby Bjorn isn't meant to last 3 years, because it is designed for carrying very young infants. Also, saying that it is a "a very unnatural position" - it's almost the same position that a wrap creates for the child, without the tight pressure on the parent's torso.

The reason the Bjorn can't be used for very long is because it basically hangs the baby by its crotch. This IS a very unnatural position. Good quality carriers actually hold the baby like your arms will. That's why they're good for so much longer. Not at all like a wrap and I'm unclear what you mean by "tight pressure on the parent's torso". I never had that and the Bjorn hurts because the weight pulls down on the shoulders. Very, very uncomfortable. By contrast, the correctly worn wrap is much more sane.

And if you could persuade a 3 year old to ride in a sling, well, that's impressive, because mine was on his feet and on the go before he was a year old.

I think you're unclear on the concept of babywearing. The point is that it adapts to the child's needs. Mine were VERY active so pushing an empty stroller around was a bit of a pain. It was easier to take the sling and when the child was too tired to walk all the way back to the car, I had it. No need to "persuade" anyone. Also, my kids weren't good "stoller babies". They really likes to run and then they'd run out of steam :/

3 year olds don't like to be confined. I think that's a no-brainer but they can't always keep going forever, especially in a busy airport or other public place.

Please don't tell me your child NEVER was held in your arms at age 3?!? I have a bad back from a pre-child injury so the sling was a lifesaver. I see so many parents clinging on to toddlers in airports and I was able to do that, with my hands free.

You say you didn't find banging into people with the backpack to be a problem, but what did other people think of it?

I didn't "bang" into anyone! I kept my distance. I also had two other children with me so if anyone had been it, it probably would have been the brother or sister first! They didn't say anything.

Since it wasn't very practical, and I only took it because I couldn't face summertime crowds in London any other way, I used it for the flight. She didn't kick anyone because of the position. Since she was a very active child, I didn't use it much.