We carried our seven-month-old daughter around Prague and Leipzig for hours in a standard BabyBjörn this last winter and she/we loved it — cozy and comfortable. The problem: it’s only a front carrier, and since then, she’s gotten heavier, which started to take it’s toll on our backs (imagine carrying a bowling ball strapped to your chest.). Now we’re using an Ergo, which can be easily re-configured for back-, front-, or side-carrying. Since it buckles around your waist, most of the weight is put on your hips. While an “original” BabyBjörn is rated for use with babies up to 25 lbs, I tried ours with our daughter when she was 15 lbs and it was a no go. She’s heavier now, and the Ergo remains incredibly comfortable: I’ve noticed much less lower back strain.
Learning to scoot the baby around your hips, onto your back, and into the Ergo without outside help is a bit of a production at first, but no problem once you get the hang of it. If you want to put the pack in front or on your hip, it’s quite simple, too (ed. note: the videos are quite helpful). Like the BabyBjörrn, the Ergo is made of cotton and cleans up very easily with just a sponge most of the time. It can be washed in a machine, too. There’s a cotton hood (the green fabric in the pic) that attaches with snap buttons for when the baby is sleeping — protects her from the elements, and keeps her head from flopping around.
Note: BabyBjörrn does make an “Active” model (which we have not tried) with lower back support that is supposed to “ease the burden.” However, you cannot convert that one to a hip/back carrier.