While the griot history preservation method is an interesting one, it has many pros and cons to it in reference and comparison to typical history textbooks.
Griot-based history preservation seems as though it would be very beneficial, as it adds an element of culture to the history, and makes it seem more palpable. It adds a well rounded-ness to the story, and seems as though it would keep it all interesting. The cultural element of history would never be neglected, as the story is passed through a main cultural element of typical societies.
In terms of cons, I can unfortunately find a great deal in the griot-based history method. Primarily, how would one be able to completely trust what they are hearing? If it is passed down orally rather than through writing, there leaves many instances for pieces of the story to become altered (whether purposefully or accidentally). Therefore, there is nothing saying that the stories being told are accurate. Also, as these stories are being passed through songs, there is also the possibility that certain details of history are being neglected.
In terms of the history textbook vs. griot history, I'd have to say the history textbook is a better choice, simply because it can preserve the information, unchanged and unaltered. The griot history method, however, would definitely be more interesting and engaging due to its cultural nature.