I just ordered the large size because it is actually slightly shallower than the medium size. Not sure if it will work in a City, but if not, I'll use it in a Part Time.
This is my small insert for the City.
First picture shows it being sitted in the middle.
Second picture shows it bring sitted at the side. Notice plenty of room in there? I reckon medium or large would be better.
thanks for the pics, i've been dying to see how the large fits in this bag!! i ordered mine on monday but still haven't received yet. hopefully i'll get it today.