My browsing around the internet for alternative network devices to use as a Time Machine backup target, I came across the following thread:
In it specifically, here is the bit of interest:
Unsupported but well-known alternative: enable a hidden option that allows you to use any network drive. Open the Terminal application and run this one command:
defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1
It will allow you to select any network drive from System Preferences: Time Machine.
The network drive should be a HFS+ file system over AFP.
So at the end, he says that the volume should be HFS+ and have AFP enabled. However, in looking at the command, it does say 'UnsupportedNetworkVolumes'.
If SMB volumes still fit into that category, we might just be golden.
*Anyone have some Mac's and willing to test?
* = this is simply putting some two plus two together and hoping it comes out four-ish. I take no responsibility if your computer is broken, space aliens appear in your front yard, etc.