Clearly one argument against expanding beyond ASCII would be disagreement over which letters to include!
This (and what follows) is much of why I argue for using only the ANSI extensions, and even those only for custom (that is, user-defined) atoms. I've already made some private notes for the use of Ä, Ç, Ê, Ë, Ñ, Ø, Ô, Š, Þ, Ü, Ž, and ß (as well as V), some of which I've shared already, but your uses of those characters on an ID could (and probably would) be different from mine.
And as H.G. points out, notation for hexagonal, triangular, and 3D (or more) layouts could (and probably should) start from scratch for meanings. Even so, I can imagine running out of atom letters quite quickly (especially in the last case), and might even overwhelm the extra characters of ANSI, in which case I could see expanding to Greek letters or even Latin Unicode.
...whereas you'd (presumably) take exception to ⟨Ƿ⟩ or ⟨Ꞵ⟩ (assuming those even show up for you).
Those did show up, and you already showed one example of where different people would use the same letter for different things: you'd (apparently) lean toward using ß for Sexton, while I'd use it for Switchback. And we could; I'm not in favor of standardizing the ANSI characters, but rather making them available for use when user-defined atoms are implemented (and I'm not expecting that before the end of next year at best).
This (and what follows) is much of why I argue for using only the ANSI extensions, and even those only for custom (that is, user-defined) atoms. I've already made some private notes for the use of Ä, Ç, Ê, Ë, Ñ, Ø, Ô, Š, Þ, Ü, Ž, and ß (as well as V), some of which I've shared already, but your uses of those characters on an ID could (and probably would) be different from mine.
And as H.G. points out, notation for hexagonal, triangular, and 3D (or more) layouts could (and probably should) start from scratch for meanings. Even so, I can imagine running out of atom letters quite quickly (especially in the last case), and might even overwhelm the extra characters of ANSI, in which case I could see expanding to Greek letters or even Latin Unicode.
Those did show up, and you already showed one example of where different people would use the same letter for different things: you'd (apparently) lean toward using ß for Sexton, while I'd use it for Switchback. And we could; I'm not in favor of standardizing the ANSI characters, but rather making them available for use when user-defined atoms are implemented (and I'm not expecting that before the end of next year at best).