an interesting, dare to say an unique bike but to be honest it tries too hard to meet road and gravel worlds. Who will enjoy road riding with friends when you have over 2 inch 650b tire? And who will feel safe and secure on gravel descends when riding on bike with this kind of geometry (a short bike with short stem). But I applaud bike companies who try to push the envelope. Like a few years back Cannondale did with Slate model and Open with U.P.
I don't know nothin, but on the road I would do the 700c wheels, and gravel the 650b wheels. The short chainstays and short stem may not be a problem with a longer top tube and extra slack head tube. But I haven't ridden the thing. Either way, I would buy it over the warbird (pending a test ride) as the warbird was a little to sedate feeling for my riding style. Personally I need something that can do tight urban riding, smooth single track, fast road, and gravel. A bike that handles like a crit bike with larger tires works for me. That isn't your typical gravel bike though - like you said its not great for loose gravel descents (for those lucky to have such a thing).