In /etc/fstab, I mount a number of drives on boot and set their name with x-gvfs-name=. Dolphin shows all of the devices in the "devices" Tab, but if a device has a label set (as shown in /dev/disk/by-label), Dolphin displays the label name, not the name set with x-gvfs-name.

I would prefer to handle naming in one place. Is there any way to force Dolphin to use the x-gvfs-name rather than a label?

Not AFAICS, but Dolphin is not a Gnome application, and x-gsfs naming is a Gnome specific thing.