Three-band linear gutter-bank in Florence (ICASSP 2014)

ICASSP 2014 in Florence has just ended. The slogan was "The art of signal processing". In Florence, Art is indeed everywhere, and science, signal processing included, is not very far apart.

Take for instance this example of an analysis/synthetis three-band, apparently linear, and complex gutter-bank. I do suspect a certain redundancy i cannot yet understand. Is it related to other diffusion-based filter-banks?