I am just using wifi at the moment. My experiments of image capture were only of test shots (Large JPG - not RAW) and they were being stored on the micro SD card local to the Raspberry Pi itself. I have not looked into the USB sharing option but that did sound like an option - basically using the Raspberry Pi as a gateway. But - I would like to try the RPi as the server and just access everything via VNC Viewer via my laptop on the same wireless n/w if my wireless throughput holds out.
I can upsize the micro SD card (currently 32GB) I guess and continue to store local to the RPi and just preview over VNC or maybe I'll try a n/w fileshare or FTP
It's a bit impractical for me to connect via Ethernet but I do have a Ethernet over Power option I could try if the wireless doesn't come to the party.
What router are you running ?