I've been temped by the idea of selling my 45 and 70 for the 30-90mm.
Never used this zoom personaly. The owners feedback is variable, from brilliant at 30 to 70mm to clearly weaker than the 70 prime at f5.6. It looks like the zoom is a very good option for wide angle as we mostly shoot at f8 to f16 anyway. But if you're used to your 70mm you will have hard time selling it for the zoom.
I stopped thinking about the zoom when I realized that a D810 + 24/70mm (new version soon) is half the cost of this lens. A D810 + 24/70mm is also 30% lighter than a S + 30-90mm. If some flexibility is needed I'd prefer this option.