My lovely reader provided some photos of the City SoftShell in her upper and lower sizes. She varies in tops between size 4 and size 6, and ended up opting for the 4 in this coat. The size 6 has a lot of room for cozy layers underneath, but to me it looks like the size 4 also has plenty of layering room for thicker sweaters. Possibly not a scuba hoodie, but definitely a thick sweater like the Chai Time II. She loved the jacket and could not leave it behind so she opted with the 4 after trying both sizes several times.
Size 4 on the left, size 6 on the right