It sounds great, but in practice it really doesn't work. It's not just the vastly different power levels, it's the vastly different scope of the threats each splat is facing. In Vampire your main concern is internal and external politics. Meanwhile Werewolves are in an all out war with Cthulhu, and Mages are battling an enemy that routinely rewrites reality itself. These things are not compatible.

It was a desperate attempt to create some level of compatibility that lead to New WOD, but that didn't really solve the problem and in the process it destroyed most of what made the individual splats interesting in the first place.

You're better off with something like Dresden Files if that's the kind of game you're looking to run. WOD isn't really set up for it.