[midenginedcoupe]

I'm not entirely sure who's the target audience of this new notation. I've been reading music for 40 years and don't think I've once needed the vertical gaps between notes to tell me whether an interval was a major or a minor third. In fact, I think in terms of steps in the scale, not whether those steps are flattened or not. So equi-distant vertical spacing for the notes in a major scale better fits my mental model.

But that's just my own preference/habit. The real sticking point for me is the ambiguity of whether a note head is exactly on a line or just below. Sight reading needs that decision to be immediate - picking out whether the note is just below the line inamongst some large and rapid intervallic jumps is going to be almost impossible.

Also, I'm not sure the author has understood one of the key rationales for these other clefs - that the number of ledger lines can be minimised. E.g. Playing in the upper register of the trombone is an exercise in parsing 4-6 ledger lines, which can get tricky especially with rough hand-written charts. Switching to tenor or even alto clef keeps everything nicely within the stave and easier to read. Where in the staff the 'C' sits is just a detail, and it's surprisingly quick to get used to different clefs with different centres.

[sfblah]

I basically agree. On a piano, this notation has the significant negative of making it unclear which notes are played on "white" keys and which are played on "black" keys, in the key of C. It's pretty useful to have that explicitly marked.