Good question.
I'd never thought to try it before, but it turns out it does work.
The only problems with using a real FV battle system, is that the block animation has nothing to play on. The sound effects trigger like a normal skill animation though, so there is some audio feedback.
Additionally, the MV version of this plugin doesn't have a 'block' damage popup, so there's no feedback that a block occurred at all except for the sounds from your block animation. This is because MV gets all popup text from a system file, while MZ draws text on the screen, so the MZ version of the plugin could show a block popup when a block occurred.
Anyways, it does work, which frankly surprised me.
~Ramza