Fantastic plugin, really excellent work.
My suggestion for the tool, would be when you select Draw, have CTRL or ALT or something be the Inverse Draw. Basically while I am working on a morph, if for example Draw too much and it's Bulging out, I want to be able to just click a key and have it now do the opposite and Inverse Draw. So I can just pull and push quickly without needing to go into the UI and change the Brush. So if I pick for example the Inflate, and I click Shift to apply the Inflate, it would be great to press something like CTRL to De-inflate. I noticed the Erase works good for undoing, so maybe having that on a hot key.
Of course if there are ways to do this now, that I am simply missing, then by all means please point them out to me, I appreciate it.