"By creating the LFR1100 Active we had an incredible amount of control over the five driver sets which allowed us to experiment with making the Listening Window and the Sound Power the same."

This statement is telling us actives alone won't yield a null Directivity Index. We need active LFRs to experience Nirvana.

I'd really like to understand, in terms of soundstage, imaging, etc what the qualitative differences are between passive, active and active LFR.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated