Just a few observations in no particular order from my point of view (classical violinist and pianist--performing professionally for 28 years, and a music theorist studying the structure, composition, and history of the above for about 20 years.)

1. This, and all other similar modern attempts, is interesting in that it has so much in common with the very earliest forms of music notation. We have as a basic, "this is me telling you how this is supposed to sound" example as far back as the 7th century, in which you had written words with markings above, below, and around that are meant to guide chant practitioners about where to go next to shape the musical phrase. This is also the origin of modern punctuation in written language.

These attempts are remarkably similar in my mind to the early attempt to guide people. They strike me as memory aids more than anything. As in, I've heard this before, I know how it is supposed to go, I just need a little help here.

When I say origin above, I'm talking about the western tradition of music. The eastern tradition of music evolved very differently (both in terms of music notation and the notion of punctuation), and you can trace early concepts of music notation back a couple of thousand years b.c. But I'm not talking about that.

2. The history of music notation roughly follows the history of the study of music theory in a cycle: is the point to understand and describe what happened in the past, or is the point to prescribe what should happen in the future? People have been fighting this battle for centuries (again, there's a parallel here between language and music), and we continually go back and forth.

Notation methods carry that same problem with them. What are you trying to do? What problem are you trying to solve? I'm not going to say that modern standard music notation is perfect, but it's a good balance of both prescription and description.

3. Speaking of balance, there's another element that's been mentioned already: creation vs. performance. A good method of notation has to be easy to write, not just easy to read. It has to be specific enough that composers who want to care about details can clearly define them, and I think this method is sorely lacking in that regard.

4. Re: ledger lines. These are a modern, notational "convenience" that was brought about by printing technology making it reasonable. And because performers hated music without them. Music before the 18th century did something that is much more reasonable in my mind, but in practice is difficult to manage. The clef symbols used to be moveable. They sort of still are. The difference between alto and tenor clef is that the c is on a different line.

In pre-Baroque music, there were only 4 staves instead of 5 and the clefs moved all over the place to accommodate the fact that there were no leger lines. The clefs would switch to a different line in the middle of a phrase or just change completely from a c-clef to a g or f clef.

This kind of shifting around is, needless to say, extremely taxing on the performer. But very convenient for the writer and publisher. Leger-lines were originally an acquiescence to the needs of the player, believe it or not. But you know, give someone an inch, and they'll write Strauss.

5. These kinds of visual aids have existed forever in music. But they are only useful for the performers. Writers of music have to consider vertical relationships between notes. I mean, they don't have to, but we're stuck in a musical rut where we've collectively decided that the successful music is going to be based on some permutation of I-V-I. And that's even more true of modern i.e., popular non-classical music since about 1940) than it is of modern classical.

You need to understand the conventions, and visually seeing "difficult" intervals is key to helping you write music that conforms to those norms.

In my opinion, modern standard notation is almost as good as a syntax highlighter in terms of seeing parallel 4ths, 5ths, octaves. It's not quite as good, but it's close.

The proposed redesign is . . . not so great at that.

6. Portability has been addressed by others, but I haven't seen the scalability argument yet. Let's say this works well for one person playing alone. What happens when you try to get 4 people to play together? What about 100? What about 1,000? Someone has to look at all of that and figure out what is supposed to be happening and then lead the group and know when things are going wrong. (I've conducted concerts with 8 harpsichords playing at a time. There is no way this style of notation would work.)

7. I just don't think this is viable as a redesign of piano music. A learning aid? Maybe.