In line with the whole discussion, let me re-post some of the comments by Minoru Inaba about ki and aiki. It's a very good and important interview and it's found at:
First a quick comment in the interview about what should be obvious; this form if "ki" power is used throughout Japanese martial, including koryu like KSR:
How do you separate or unify the technique of Kashima Shin-ryu and aikido?
For each art I teach the basic form. But I always keep flexibility in mind and am not trapped by the form, while at the same time I do not neglect technique.
In my limited experience, I have felt that while teaching the technique, the important point is self-control, calming the mind, and "ki" energy.
Then a comment/discussion about ki and aiki:
How can you put forth offensive power? The first thing you have to do is to focus the power in your center. Offensive power will naturally flow if you focus your power in the center. That is forceful power (iryoku). It is a condition of focused energy that becomes center energy. In budo, people use the terms "bui" or "iryoku", don't they? Most important in martial arts is "iwoharu," showing this powerfully focused energy. It's not good to pretend that you have energy (karaibari). Try to use the energy in the lower abdomen. You can call this energy focused "ki" energy. If you don't have center energy, you are bluffing. Really, you have to develop this energy. The energy will flow naturally if you can focus it in the lower abdomen. If you understand this point, you will understand how to develop your body and mind and how you should train.
If you forget this essential point, you'll think only about winning, and you won't have the power to keep centered. This power won't be released and you will be destroyed.
You do exercises to straighten up your back muscles and relax your shoulders. Drop your focus to your lower abdomen. If you do that, you'll find your center point and you will produce center energy. If your center is not developed, you won't have ki energy available to project through your fingers.
If you take excess energy from the upper body and train the lower body as in sumo wrestling, and if you train the energy of the lower abdomen, you will develop your center energy. You use that power wherever necessary.
Even though you focus the energy in your lower abdomen, you will not be able to move the energy to the area where you need it right away. You have to think about how you are going to move it. You have to think about two things, gathering and filling up the power, and then moving the power to where the opponent will attack. Also if you have a weapon, you have to project energy through the weapon. If you understand this point, you'll know how to train and what you need to develop. At the same moment you meet your opponent, you focus on your abdomen (hara) and project your ki where you need it. The result will be that you will shut down your opponent's power. I understand that as the power of "aiki."
Then a further re-statement about aiki itself in relation to the technique/waza that is jujutsu (althoug of course the waza is also done with the ki-power imbued in Nage):
"What is Aiki Technique?"
Make the Opponent's Power Zero
When power meets power on the battlefield and you think about what aiki technique is, how can we overcome the opponent's power and make it zero? I think this is the point of aiki technique. Make the opponent's attack zero; take away the opponent's way to attack again, and overcome the opponent's fighting spirit. These points are important when you think about "jujutsu." Daito-ryu uses the term aikijujutsu. Aikijujutsu is the correct expression. Initially, aiki neutralizes the opponent's attack; then jujutsu is used to remove the means to attack thus also defeating the opponent's fighting spirit. That's why they say "aikijujutsu." If the technique reaches a high-level, these two elements will occur at the same time. When the opponent attacks, he will be immediately thrown. That's the level of an expert.
Originally jujutsu had both elements. If you look at "aiki" and "jujutsu" and you want to polish aiki technique, the point is that you receive several types of attacks and, at the same time, you make the opponent's power zero. If you practice only one pattern of attack, then you lose the ability to apply techniques in different ways and they will become mere form. You must be able to respond to several types of attack. The crash of sumo, the punch of karate, and even the contact in rugby and soccer can be counted as types of attacks. A thrust from a small knife is the same. You have to respond. With each passing generation, the way to attack changes.
These are the endpoints that I wanted the workshop participants to have an insight into and a few starting abilities in that direction.