Well, the MEP engineering firm just left and the principal stopped in my office to thank me for the great training my techs did for them. We were looking at model of an HVAC system and he said the most profound thing. He said "It's all there". I asked him if when working in CAD, had they ever created a set of documents with everything. He said "no, that's impossible, there are too many things in the building."
So, what do you get with BIM that you don't get with CAD? Everything. The complete system. There's no faking it with Revit. Either you know how to design an plumbing, electrical, HVAC or fire protection system or you don't. Once it's all there, you can go on to the next project and not get bogged down in RFIs and field administration.
Welcome to "the end of the line!"