FWIW, I did a short series of articles for Mustang Illustrated Magazine back around 2000-2001 regarding the TP. I used Brother Lon's engine as the basis for the work, and part of what I did was to compare, side-by-side, both the single plane and dual plane dual quad intakes. I don't remember exactly what the Superflow said in regard to numbers, but we flowed each runner and found that the design, both single and dual plane is quite admirably balanced. And there isn't a great deal of extra flow from the single plane.
I'll try to find my own copies of those articles.
KS