So after all that rambling… is there a respectful way for me to ask Sensei if to demonstrate these technique "at speed" (preferably with me as Uke) I am worried this will sound like a challenge or be seen as disrespectful. I am not good with words and would hate to offend anyone.
Yes, there is a good way to do it. Tell your instructor you are interested in a training when second and even third attack is possible( when a technique against first attack fails ). It is called henka waza.
In some dojo it is a part of regular practice.
The actual speed/power of your attack has secondary importance if Nage(this who execute a technique) has enough training under his belt. In higher level of practice, the difference between the roles (Nage/Uke) is not clear, because you may recover from a technique and initiate a new one and it also can be countered etc...etc... This kind of practice we call kaeshi waza and should be practice regularly, however not by fresh beginners.