Not sure if this is just an X3c/d thing or whether it was fixed in previous versions of X3, but although I had excellent luck with V-Vocal, the one problem it did have was occasional crashing when inserted in Take Lane clips. Last night I was working on several Take Lane clips with V-Vocal, and there were no problems.
The other difference I noticed was that V-Vocal no longer generates a new clip on top of or behind (it never could quite seem to make up its mind) the existing clip. Some won't like this because they don't have an automatically generated "safety copy," but I prefer it as I always had to go in and delete the old clips anyway.
Although Melodyne is great, V-Vocal has some features I use a lot so I'm glad both are working well.