i got these to replace some 200s from 4-5 years ago, since i lost some weight, and find icebreaker sizing to be a bit inconsistent anyway. the weight on the these is perfect, from wearing around the house as pj's on their own to under heavier schuller-fabric type pants for cool-weather hiking, skiing or evenings camping. (for really cold winter camping or sitting on a ski lift in low temps, though, i'd go for something heavier.) i know these leggings should hold up and are great quality. i like that the waistband isn't super-high, and the elasic does not cut into me. i ordered both a small and med. and am returning the medium. i'm a little under 130 with slim hips and went by my hip size (36") rather than waist size. the medium would have been okay but i know they stretch and i like my leggings very close-fitting. (my old ones are a large and are huge on me and were even a little big when i was 20 lbs. heavier. i keep them to go over other leggings when i want a double layer :) the only thing i'd like is a little more length; i'm somewhat tall but just under 5'8" so i don't know if the really tall would like these. also, the old icebreakers had different, pretty floral or doodle-y designs at the hip or ankle. not sure about the new design (or any design at all) at the ankle since i also like to wear these as plain leggings under skirts. but i do miss the little hip design. the blue color (horizon) is very pretty, nice change from black!