i asked JE's customer service, they said the measurements for the kith x JE SS hoodie is pretty accurate and that you should go with your true JE size, not a size up from your JE size.
maybe he might drop it a week after this... just like the summer-weight denim collection which he released just a few weeks after dsm.. idk just assuming lol
oh wait i wasn't referring to the waist. i was talking about the front/back rise or the inseam and hips etc. not the waist cause its elastic anyway. appreciate the response tho!