I do this and, unlike in this article, I am able to have the remote backups work. I did it with iSCSI and GlobalSan for Mac OS X over ethernet and backups are done locally. This was done because this they had a type of min-SAN that you can connect via ethernet instead of fiberchannel. Actually, we ran it this way for a while, then switched it to locally hosting the database and just doing backups on the remote volume.
Keep in mind this is not recommended because a database needs a high reliability connection and ethernet is inherently unstable compared to a serial connection (SCSI, SATA, USB, FireWire, Thunderbolt). So if you must use ethernet to connect to a volume, make sure there is only one highly reliable and fast switch between the storage and the computer and Cat6 wire, etc. I do see why FileMaker does not officially support this even though there are some workarounds if you want to take on the risks and do what you can to minimize them.