How can I backup and restore Google Now Launcher home-screen layouts? The only times I've seen a successful restore of the Google Now Launcher home-screen layout is when it is the default launcher from the onset as the installer goes through it's motions.

Restoring a backup from Titanium Backup does not work.

I've also tried making a recovery flashable update.zip via Titanium Backup but it still won't restore the home-screen layout
Try backing up the entire Google app, not just the Google Now Launcher as it does not store any data itself.  

Backing up the Google app (and you can try the Google Now Launcher) in addition to it, should work.