Raspberry Pi 3 is a great low power device for this task but I have encountered a few issues.
I am currently running a network of five Pi 3 devices. One of them is at a remote location and I can’t visit that location often. That Pi syncs around 12000 files daily to the other devices. This creates too much load to the mounted USB memory. Already after a few months one of the USB memory devices has failed.
The internal SD card of the Raspberry Pi may also get corrupted if there is a power outage or a surge. This has happened to me too.
In other words, if you decide to use a Pi 3 make sure you don’t do excessive amounts of writes to the USB memory or to the SD card. If you’re going to have it in a location with somewhat unreliable electricity you have to use a UPS.
It might be better to go with a “real computer” with spinning disks or good quality SSDs that can handle the writes.