(maybe a choice between a dislocated elbow and safe ukemi but still a choice)
While technically a choice, it's one most people would never make, but the chance to even perform ukemi as an option is only earned through practice. Depending on nage's execution of shihonage, as you say, uke has the choice, but it has to be perceived.
The shihonage that ends with uke in a backfall position before nage, I believe, would likely produce the same effect on an untrained individual. The shiho that calls for a breakfall escape is not a throw so much as it is a nasty arm bar. An arm-f.u.b.a.r. if you will, and someone with no clue of what was coming should expect to hear some grisly popping sounds.
That makes me wonder about the actual use of some aikido 'throws
'. If you actually did a kotogaeshi, or kaitenage on an aggressor, it seems you would have more likely a chance of wrecking a joint or kicking someone in the face.
dunno, happy friday folks. Seminar tomorrow. I doubt Koshi is on the menu, but I bet it could be arranged.