My Just Ear's are far and above the most comfortable CIEMs I've ever had. The measuring process is extremely labor intensive and it does feel that Sony has given a lot of thought about the actual wearing process of CIEMs, down to the cable material, placement of the cable exit, materials for the canal, etc.
Before I had the MH2 Fitear would have been my choice for the most comfortable CIEM, now if JE is a 10/10, Fitear is about an 8.5, qdc an 8, and everyone else I've used (Westone, UE, JH, VE, UM) doesn't even get a 7, US brands are more of a 4 or 5.