Split an Apple-supplied Fusion Drive back into two separate volumes? Is it possible to take an Apple factory-created Fusion Drive and downgrade it into two separate volumes?  I understand this would also necessitate reinstalling the OS and Recovery Partition etc.

The reason to do so is that the company-mandated Sophos SafeGuard disk encryption software won't work on a Fusion Drive (unsurprisingly), and FileVault 2 is prohibited (for now).
Yes, you can split up a Fusion drive:

http://www.macworld.com/article/2015664/how-to-split-up-a-fusion-drive.html