As a huge fan of Plan 9, I would strongly recommend against acme for visually impaired users. It's highly mouse-driven, requiring a spacial understanding of the interface and the ability to see where the mouse is and coordinate its movement to execute commands.
Good point - didn't think that through enough before recommending.
Just thought of as nice tiling editor.
Thoughts on Sam? It seems to me like it might be a much better fit, esp. given the ed-like command only mode. (And I always liked it better than acme anyway...)