Paal, I am sure yours is a positive input. To find an answer to your question, I suggest to read the paper by Fagiano et al. (it is linked at the bottom of the paper). It is a detailed simulation of the forces involved in the operation of a kitegen "yo-yo". The results are very encouraging; the yo-yo is not at all like two horses pulling in opposite directions. But I understand that it takes a while getting used to the idea; it took a while to me, too!

Thanks and sorry Ugo - I forgot entirely about that haul-back procedure when posting this LeviS analogy. SO LET IT BE UNSAID.
And i agree that if 12% of generated energy is all it takes to bring the Kite back for 'a new round' , that is quite encouraging.