Hey Peter, thanks for your post!
I am pleased you are getting the “Ku” attack happening. As I made reference to in a video, it is as much a general technical/efficiency development skill as a useful articualtion option.
You are talking a lot about personal sensations i.e. middle of the tongue and close to the roof of the mouth, that may or may not be exactly what’s going on so my questions to you are:
1. How does it feel?
and more improtantly
2. How does it sound?
If it is working for you and it sounds good and feels free, then go nuts. Just to be clear, this is just one of the 5 articulations and also airspeed thanks to tongue position isn’t the main factor in pitch change (I think we are cool with that as you put SHAPE in brackets!!!)