XS Scuba Companion or Dive Rite TravelPac/VoyagerPac

I'm looking for a BC for my fiancee and she's quite small: height 160cm(5'3"), 48kg(105lbs). Usually when we dive in warm waters with 3mm suits she wears 3kg(6.5lbs) of weight. She likes XS Scuba Companion with 30lbs bladder and Dive Rite TravelPac that has 27lbs bladder or VoyagerPac with 35 lbs bladder. Unfortunately, around here where we live there's no way of trying out any of them so we spent a lot of time researching different options. Would XS Scuba Companion with 30lbs bladder be enough for her even with 7mm suit in temperate waters? Since she doesn't need much weight I'm hoping 30lbs bladder would be enough? Or TravelPac? I would greatly appreciate any advice on this since I can't figure out would bladders of that size work in both warm and colder water...