Dabiri’s work is documented on Betz's law: validity and limits. And also the paper in reference on Betz limit and power available in the wind mentions the known Betz’ limit of 16/27 for drag systems, and 4/27 for yoyo systems.
In my opinion a AWE-farm should not be arranged like a current wind-farm, but could share a frontal airspace. with several floors for several unities (a single gigantic kite would be desirable but not possible), avoiding both blockage and a too large space use.