I’m primarily a pianist and a composer, but I do play the guitar with a sufficient enough level of skill and knowledge to appreciate and approach TMDC from the view point of a guitarist. Although you’ve created TMDC for guitarists; what you’ve actually invented is a musical tool that can be used by musicians in all walks of life.
My first use of the TMDC was with the piano, using it as an improvisational aid. Without blowing my own trumpet, I would say that my knowledge of harmony and my improvisational and compositional skills are advanced. I’m able to sit at the piano and make things up on the spot, in every key under the sun and in a multitude of styles. Even with my experience and knowledge I still found the TMDC an excellent aid.
No matter how much you practice and how much knowledge you think you have its always good to have a reminder there in front of you. It can also shake up playing habits.eg. Say I’m playing in G# Dorian and because I’ve got TMDC in front of me, I end up using a min 9th chord were Id usually use a completely different extension in the same situation. Although I wouldn’t use TMDC all the time with the piano, it’s without doubt an excellent and interesting tool for improvisation. It gives me an approach and option I didn’t have before. Thank you.
TMDC teaches guitarists how and where to play the modes, but the wheel on the first page of TMDC could be used by any musician, on any instrument, if they already have a basic knowledge of modes.
But now to the meat and bones; the TMDC was designed to be used as an aide for guitarists and here it really shines.
I think your design and its implementation is nothing short of ingenious. Having the ability to find each individual mode so easily at the three different locations is what makes TMDC such an extraordinarily powerful musical tool.
Most people, especially beginner musicians find modes daunting and intimidating but your device should give confidence to guitarists everywhere. There is of course a small learning curve to figure out the system, but after ten minutes I was happily noodling away all over the fret board.