Sounds like a good way to get hurt to me.
We often do waza quickly, fast, hard, etc.
I just don't think I need to either feel full power/full speed from a relatively young, still quite fiesty 7th dan. He can throw me quickly, or hard, but preferably not both at the same time, and not full on. Maybe someone under 47 without herniated discs in their neck would feel differently.
As to surprising people...I tend to dump people pretty hard who do tha to me. They rarely do it twice. Sometimes people end up going to the ER after stuff like that. I can understand doing that for a limited period of time (such as preparing for a dan test), but on an ongoing basis? I think that is just begging for an issue.
I am well aware of my body, when I know and feel that I can do an attack (demonstrating a live one with my teacher) than I'll do, of course there are chances of getting hurt due to unintentional hit from a technique by my Sensei, but they are very rarely.
Not only that, when I help my Sensei demonstrate a "live" attack, it helps my sensei, helping me (how to take ukemi to a higher level), help the student who watch how the timing of an execution should be like and how to take ukemi from it.
We usually do 2-3 times fast/hard than again slow and soft.
when working with higher rated ranks, we work on fast pace and sometimes slow pace, when working with kids, its slow pace only, guiding them and showing them and let them figure stuff on their own.
Buck has said it well that "You don't learn much if you don't commit to your attack" this is true. However in the sense of Aiki, it's not true, since hurting other is like hurting your self. so the right balance is needed (fast/hard & slow/soft).
It's been like that for the past 3 years, so pretty much I know how to work with my sensei, and I doubt new-commers will try that, since they will probably get hurt.