It hasn't taken away the previous Diffusion parameter, which still diffuses/crossfeeds the multiple taps together. It simply adds a new parameter, and based on the name, my guess is it is placed just before the 4 Delay lines split off.
I tried it very briefly and loved what I heard on all the types (enumerated in the release notes) except Plex Shift. Either it wasn't working there, or I wasn't doing something right because I was rushed for time. But full Diffusion and Input Diffusion on the Plex Shift still left plenty of noticeable repeats (where it practically turned Plex and Plex Detune into reverbs).