I am trying to use the command, Texture- Purge unused shaders from the menu bar, I get an immediate crash. It seems anytime I try and delete one of the substances from my scene it crashes instantly. Unless I go into Modo 801 (which doesn't support substance, yet) and delete it. It works perfectly fine in 801, which supports the theory that the command is trying to delete substance materials and is failing.
I hope you guys are working on a fix, because at the moment I feel the software is still too immature to be used on projects. But I look forward to seeing it working well in the future.