If I'm familiar with an application, I don't look at the keyboard. If I'm VERY familiar with an application, I don't even recall commands through their mnemonic, but through muscle memory.
For example, I've just switched to spacemacs from vim, and one of the first commands to learn is Ctrl+G, which is to exit from any menu. "Escape from menu" is not mapped into my brain as C-g, but as "pinky here and left index finger here." In contrast, when I want to change to next buffer, I think <SPC> b n, and not "thumb, right index finger on this button, then right index finger on this button" (although I'm sure that it will become muscle memory before long.)
HOWEVER, the nice thing about spacemacs is that you can press space and you see all possible commands pop up in the command buffer. This is a highly effective method for learning commands, and it is similar to how the "ribbon design" functioned in Microsoft Office 2007. This is where I think the E-ink keyboard could be most useful: in teaching keystrokes. It's essentially the same thing as looking down at the spacemacs command buffer, but you get to see the command pop up on your keyboard.
That being said, there are a lot of downsides to the whole idea. You're stuck with a very limited set of switch-and-layout combinations if you want an e-ink keyboard. Secondly, keyboards take a lot of abuse, and I don't know how much a replacement e-ink keycap costs, or where I'm going to get one (maybe this won't be such an issue, though). Finally, the glyph can only be represented as a glyph, and not as a detailed command like it can in a spacemacs buffer.
Cool product though; I'd get one if I had money to burn!
P.s The E Ink display isn't in contact with the actual user, the keys are just a transmissive body for the display.