I mentioned this design during the discussion. For what I understand KPS used two winches while the present design implements a pulley to transfer the tether between both kites. Moreover in the current design the down path is realized by the trailing edge.
That said I think the use of such a pulley or some arrangement comprising a pulley could also be possible with spiral/return trajectories. An advantage could be removing the excess of tether, the winches and their motors to recovery it at each phase. There would be only one generator connected to the pulley and delivering energy in full time, from one then the other kite alternately. Rigid kites could be used unlike for the vertical path.
Some sources below can allow to analyse in a deeper way:
From the “Technology” page above:
The tension causes a 100-200m line to be spooled out from a drum on the ground, which is connected to a generator – thus creating electricity.
Figures 5A and 5B show a multiple winch system boo. Systems comprising multiple winches are advantageous because they allow for at least one airborne device to be deployed in an electricity generating mode while another airborne device is being wound in. As such, electricity can be generated constantly.
The winching system boo shown in Figure 5 comprises two winches 5o5 of a type substantially similar to the winch 1 described above.