After shrugging off my husband's jokes about buying a fanny pack from 1991, I gave the waist bag a try with the coordinating SSC. And I love it, WITH the SSC wearing baby on front. It fits right under baby's bum, looks great (and not at all 1991,) and fits my phone, keys, and wallet easily without looking saggy or lumpy. However, I wouldn't be comfortable wearing it under baby's bum in a back carry because I won't be able to reach it easily and I wouldn't be able to feel it if someone unzipped it with the intention of stealing my belongings. And I feel like wearing the waist sac on front with baby on back, while just as functional, doesn't have the same smart appearance. Regardless, I enjoy having a shoulder-free option for carrying my belongings while wearing baby.