I recently tried a Beco. For those of you who are new to babywearing and concerned with the safety of a buckle carrier, this carrier is for you. The Beco has special safety buckles on the shoulder straps that require two hands to unbuckle, thereby ensuring that the straps do not accidentally come open. It is a very comfortable carrier and can be used from infancy.
I used it with my 20 month old, 23 lb son as well as my 3.5 year old, 35 lb daughter. It was equally comfortable with each of them. The wide, padded shoulder straps and flat back waist buckle distribute the weight nicely. The Beco comes with a chest clip as well that can slide along the shoulder pads, but cannot fall off. Overall, it is a very well designed carrier.