i'll try to clarify my earlier post;
Don's not beating any such dead horse. 2 towers has been dead for a while. There is no solution for the HG that involves '2.' The arithmetic + politics leaves us with a very narrow path on the site plan and tower design. As time passes, the 2 tower idea will continue to fade from memory into the collective unconscious. i have no opinion as to whether or not 2 towers was a good idea. But the politics would never allow Chiofaro to build a triangular shaped wall ranging from 450-600' that blocked so much of the sky in front of Boston Harbor, with a tiny sliver of public space wedged between.
A design that is both economically, and politically viable, conformative to chapter 91 + shade restriction/s - is not easy to do.
i believe there exists no combination of 2 towers that can satisfy the 4 major design imperatives. My design meets all of the obligations but 1: It expands from the BRA's set number of 900,000 to 1,050,000 sq ft to reach economic viability.
But, the combination of mixed use w/ innovation space allows the Chiofaro/Pru development group to reduce the project from Don Chiofaro's minimum of 1.1M sq ft by an additional 50,000 sq ft.
Study it and you'll shrink the design into a margin that varies by an amount no wider than a crack in the sidewalk. It's about 20 stories of (innovation) offices topped by about 28 stories of residential.
Given the marketplace, economics and the design requirements, i believe any number of architects would reach a nearly identical design solution; and come very close to offering the tower i rendered.