Hi Christian,
I replaced first both power DS-CAC-1200W-E= with DS-CAC-1200W= ; the 9396s accepts working with both PS installed at the same time. Then I replaced one fan DS-C96S-FAN-E with a DS-C96S-FAN-I, and removed immediately the other DS-C96S-FAN-E, replaced it with a DS-C96S-FAN-I.
You just need to have bidirectionnal PS if you want to change the fan type.
I had to do the work backward, because I didn't have the wright power cord; on DS-CAC-1200W-E=, the connector is an IEC-C14, but on the DS-CAC-1200W=, I don't know the name: here is a photo: https://servimg.com/view/14997875/1380
I need Schuko power cords, but I had only C13; just for testing, I used C14-Schuko added to those I received.