Re: Ask sensei to demonstrate "at speed"?
Be careful what you ask for, for you might just receive it.
I have tried to genuinely strike my teacher on many occasions over the years. I am still trying ... Now as a teacher myself, I do not mind if a student really tries to tag me.
I first need to know that the student's ukemi is good enough to receive back what that person puts out. I still have to operate in a manner that insures the safety of the student.
I love Ikeda Sensei's statement about don't ask if Aikido works, but as if your Aikido works. We all are works in progress, but I have experienced enough instances of really good teachers having no problems making their Aikido work for me to stick with it and dedicate myself to trying to do the same.