Re: Non-aggressive way to test ability and level of understanding.
interesting idea but why are you using a wrist grab to test skill, and then making a leap to aikido working on the street
when i train i use the wrist grab as a controled way to investigate and practice how to deal with an incoming force in a controlled way. because of this i require people to apply pressure/force in a direction that i can use, the tightness of the grip can be as relaxed or a tight as the person wants, but without the incoming force there is nothing for me to work with
I never tell people that someone is going to grab them in the street in such a manner, and i think it is a very dangerous thing to teach the wrist grab as a practical technique. if someone grabbed my wrsit in the street, (all my life i have never been attacked by someone only grabbing my wrist) doing an irimi nage on them might not be the first thing i try i would go for a simple release.
however, i do tell people to break down the technique and look at how they are working with a forcecoming in, then when we move to striking attacks they hopefully can see the same mechanics at work and learn some thing that is more directly applicable