There is the Droid/Moto X touchless controls "OK Google Now" and the Android Google Search "OK Google" detection, and they are different things. The Touchless Controls "OK Google Now" supports "What's up" but the stock Google search "OK Google" does not.
I believe that Touchless Controls OK Google Now wakes to a black background screen.
I just did some experimenting and found that everything works as you said with the English (us) voice. But with the English (uk) voice the what's up doesn't work and I have to tell it to read notifications instead.
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