One of the downsides to the new Black Magic Cinema Camera has been the inability to swap out batteries. It comes with an internal battery that will run the cameras for about an hour. Anton Bauer's announcement that they have created a battery adapter QRC-BMD Gold Mountfor the camera might lure potential customers. Not too many pictures on line as of this posting.
Combined with the Dionic HC battery and Anton Bauer's optional mounting bracket you could mount this baby on your 15mm or 19mm rails and shoot for about 4 hours putting out 91Wh.