Thank you for you insight Greg
I think the dojo that I train at has a very similar iriminage technique. Its a very omote form of technique that projects ki very powerfully forward while evading the attack. The result is that you have to almost somersault to receive the technique. Sensei has done that one to me to demonstrate the power of iriminage. I've nursed a few bruises from that one more often than not.
We also do an omote form of shihonage that projects ki forward and incoporates forward movement when the final cut is performed. This means that Uke must project his/her ki in the same direction of the throw in order to ukemi and somersault to avoid serious shoulder, elbow and wrist injury. Done with power its a very difficult ukemi to do gracefully and Uke can travel about 20ft in the air before landing on the mat.
So Greg, I totally agree with you that there are techniques that make it very difficult for uke to ukemi regardless of how much guiding is done.
At the dojo that I train at, Sensei is very keen to emphasise ukemi training as part of the overall aikido training. We have had sessions which have concentrated on ukemi training.
You are quite correct to state that ukemi is more than breakfalling. Its also about the sensitivity of Uke to Nage/Tori. In all its really sensitivity training and the ability to maintain contact to sense posture, balance and direction.
I think I need to add that this form of "hard" and "intense" training is only done between experienced aikidoka who are familiar and confident about each others' abilities and skills. Just wanted to make the point that intense training can be done relatively safely if done responsibly. After all, we all want to keep training and have fun training.