I'm testing FileVault 2 with a Yosemite DP 7 VM in Fusion 7, where the VM was created today in Fusion 7. It appears that FileVault 2 encryption inside the Yosemite guest OS is behaving inconsistently, with some things working and others not.
Without going hopefully too much into NDA-covered territory, here's what doesn't appear to work correctly in a 10.10 DP 7 VM:
fdesetup's new deferred enablement options
Enabling FileVault 2 via System Preferences when using an institutional recovery key
With regards to the last one, I was able to enable FileVault 2 with the same institutional recovery key by using the following fdesetup command:
fdesetup enable -keychain -norecovery key
If anyone from VMware wants additional details, please contact me via DM.