Excellent responses all! Thanks so much for the input.
Nick, regarding yonkyo, I believe there are two accepted versions.
The first, which you mentioned is the one where the base of nage's index finger is applied to the inside of uke's wrist about 3 finger-widths above where the wrist begins. A very exciting and stimulating move - supposedly beneficial to blood pressure, and you can actually practice on yourself. I've ready about people who had to practice this for an hour at a time,,,really helps you remember "the spot." Problems is that humans don't come with standardized location of body parts, and that "spot" varies. When time's of the essence, there's little time to search for it.
Thus, the version I normally use, and I believe I just saw perhaps in Aikido Journal (?), whereby a sankyo lock is obtained and one hand slides up to work the "blade" (for lack of a better term" part of the lower forearm facing you. Then, cut down as in a sword cut.
When I've taught this I always call it the "faith move," because you've got to have faith it'll work to pull it off.
It can bring desired amounts of pain and you can lower uke's wrist all the way down to the mat, or throw.
Again, thanks all, and to any future replies!