On the flip side it is much better to have the depth pass and use Frischluft...
it's faster and it's always good to have a depth pass 
but it's not better, real 3d dof is pretty much always going to look better than something done in post.
That said if it's more than a few frames i almost always fake it, real 3d dof is bloody slow!
Dave
From a readers' Q and A column in TV GUIDE: "If we get involved in a nuclear war, would the electromagnetic pulses from exploding bombs damage my videotapes?"