I think it's really cool looking. One thing that I think needs tweaking is the exact graphical representation of the edits. I think it's smart to try and replic

I think it's really cool looking. One thing that I think needs tweaking is the exact graphical representation of the edits. I think it's smart to try and replicate what it would look like if someone were to write on your document, rather than simply strikethrough words and the like, but I think you need to go further in that direction. Right now the thin, angular red lines and tiny triangles don't communicate that association to me. They because they're so rectilinear, regular, and small, they just look like busy interface crud that's obscuring my text. They therefore have no semantic content to me and I find myself having to consciously interpret them, in exactly the same way I interpret the weird strikethrough/underline scheme of your competitors. This looks like an area where you might have to find somebody with a real professional eye; actually managing to implement the precise and rich graphical look you need in order to make your new idea work won't be easy, but I think it's hard to ignore.