It's not so much that it failed to gain traction. It was the default window manager through most of the Gnome 1 era. I used to write plugins and themes for it.

It's not so much that it failed to gain traction. It was the default window manager through most of the Gnome 1 era. I used to write plugins and themes for it. What happened was that it was very slow to transition to GTK2, and so was not a great fit for Gnome 2. At the same time, the Gnome core devs were pushing for more simplicity in the user interface and the development stack, so pushed for Metacity, the less configurable C-based window manager you mention. The neat thing about Sawfish was that its design was very similar to that of Emacs -- an application-specific lisp interpreter with domain-specific C primitives, coupled with higher-level implementation in lisp. Sawfish lisp was also very similar to Emacs lisp.