Hi Doug, I quite agree. 100 kW with 12 m/s wind speed would be the best, 1 MW being achieved with winds close to 30 m/s. The total swept area (which is not indicated) could be close to 200 m² if the diameter of each wind turbine is 4.5m as I suppose from the illustrations. The duct effect is not huge, being only 20% as stated, or perhaps more with a tire tube as a duct or even Altaeros or SAWES (S500, S1000, S1500), but without aerodynamic lift.
That said I think Altaeros and SAWES are (or were) perhaps good AWE projects for two reasons: using technology of traditional wind turbines which works better than other wind systems, and the protection of the wind turbine(s) inside the duct.