The 30K was way too small on me in both the band and the cup. The band was uncomfortably tight and stretched the cups so they seemed wider than they actually were. They ended up going right under my arms and almost to my back! Not good.
I definitely prefer narrow but deep cups and I am afraid Curvy Kate bras are not like this. They have wider cups which are on the shallow side (but not overly so), which makes me sad as the designs are so beautiful.
The cups did not poke or chafe, despite being so small on me.