I'm really going to miss when Mariam gets too big to fit in a carrier. With her being colicky the first few months, and also having a toddler coming along when I go places, it's really been a life saver! I started off using a Bjorn which I loved because it was so easy to snap on and take off, but once she hit about 13 lbs, it really started doing a number on my right shoulder within about 10 minutes of using it. I have knots on my right shoulder that tend to flare up so it just wasn't agreeing with them anymore.
I started using the Babyhawk and learned how to get it on and off quickly. Sure there are no snaps like the Bjorn and it involves some tying, but it's still pretty easy. When Mariam was a newborn I did find it too difficult to use. I guess because of the lack of head control and her being so delicate, I felt really intimidated by it. Now it works perfectly for us.