Has anyone successfully setup FTPS offloading on v12?
I haven't yet, but I assume it just a matter of setting up your vip with a clientssl profile and an FTP profile with the "Allow FTPS" option checked.
Nope, this won't work. Here is why, the description of the "Allow FTPS" option :
Allows explicit FTPS negotiation for SSL or TLS. During this negotiation, the virtual server transitions to pass-through mode and the traffic is encrypted. The BIG-IP system can no longer inspect FTPS traffic after this transition
Try this article instead : https://devcentral.f5.com/articles/ftps-offload-via-irules