Have a look at http://terpstrakeyboard.com/about/ and the janko keyboard

I know neither is about music notation per se (but about fixing the piano), but it is analogous: Music notation has exactly the same problem as the piano -> it defaults to C, which makes everything else relative to C and overly complicated.

For the record, I don't think this means we should switch to a new system, but it is usefull to recognize that it is suboptimal, if only to be able to accept it and continue (because nobody is going to translate everything to some new notation)