Binary-style diffusion like in the Alphas is trickier to pin down spec wise because there are many things happening, it's a gradual transition and blend of both absorption and diffusion. These are audible throughout the mids & highs, they just sound different than either absorption or diffusion alone. GIK has not had the diffusion performance tested, there aren't many places set up to test diffusion, but it could happen at some point.
One of the benefits of this is that the panel is inherently balanced, so you can treat an entire room with Alphas and it will sound wonderful. It also means the Alphas are a more broadband device than a dedicated diffusor, so even though they have less total diffusion than a QRD style diffusor, they are also improving things in other ways.