I understand that all of you practice nikyo in such a way that uke can decide to "leave" the contact by "going down"? Is this acutally possible for uke in your way of doing nikyo if tori does not want to let him go?
There are at least three versions of nikkyo being discussed here:
* Cranking on the wrist, making it a pain-compliance technique.
* The way I personally do nikkyo.
* The correct way. (Which I hope my version resembles, but which I don't claim to yet be able to achieve all of the time.)
In the platonic ideal of nikkyo, it is not possible for uke to break connection, but that's okay because his wrist isn't in danger of being injured. It is possible for him to gain some distance by dropping; how effective that is depends on whether nage chooses to let him go or not.
In the pain-compliance version of nikkyo, changing the relationship between uke and nage, whether by going down or by other means, takes the pressure off uke's wrist. That's one reason why this version is not actually all that effective.