No - turned out conditional rendering does not allow conditional pipeline barriers. Same limitation as with NV device generated commend buffers. Neither can handle proper control flow with dependencies.
So the request keeps upright.
I would not care much if it's true device generated work like in CL2.0 or proper conditional command buffer execution as in Mantle. But if you ever touch this it would be great if it could handle multiple queues and sync for async compute as well.