Re: Ueshiba's Aiki
I won't attempt to speak for either of my teachers, or for whatever community is referred to in "I assume this is also considered a non Aikido non Aiki trick?"
Speaking for myself, I consider it a non-aiki trick "when Nage moves at the last moment to a place that is not what Uke expected". It's a cute piece of timing, fun to do, worth practicing, sometimes effective. But will it work against an attacker who knows how to stay on balance even during the attack? Who knows how to follow up with a second attack without pause?
People have said it already and I'll say it again: Aiki training doesn't replace Aikido. You can still do all your fun tricks and big throws. It's never going to be the only tool in your bag. But I do believe it's a critical tool.
Ken says, "The way this get's translated to waza is to stop Uke and then do something TO Uke. This is not ideal." -- No, it's not. It's also not what anybody is teaching on on the IP/aiki side of things, so far as I know. You may be right that it's what's happening in your Daito-Ryu video. It's not what anybody is trying to import into Aikido.
Ron, I pretty much agree that breaking balance is a consequence of proper connection, rather than a primary consideration. And if by "blending" you mean "not opposing uke's power" I can agree with that part too.
Here's an example that may help: Consider responding to yokumenuchi with a shihonage. As I was originally taught the movement, you "attack the attack," delivering atemi with, say, the right hand while blocking the attack with the left and guiding that hand in front of you into the shihonage grip. When you blend, as I understood the term, the block becomes less and less forceful until you're just matching the strike, leading it forward in the direction it's already going, and redirecting it. You can even lead the movement a bit, encouraging uke to strike a little further than they meant to, bringing them off balance even before you engage.
So far so good. And are we not manifesting yin/yang or in-yo-ho? Our right side goes forward in yang; our left receives in yin. We rotate around our center.
But according to my current understanding, this is not in-yo-ho. Though we are turning, we've built up angular momentum which has to be overcome if we want to stop or change direction. That momentum restricts our ability to respond to changes in the situation.
As I'm now practicing the movement, the right hand spirals out while the left coils in. Each arm balances in/yo in itself; each side of the body balances in/yo in itself. Externally, the movement looks very similar; internally it's very different. If I want to stop the movement right in the middle I can do it just by stopping; there's no momentum to overcome because all movement is from center. And uke is unbalanced from the first moment of touching because I'm not aligning to and accommodating his strike; I'm receiving it into my center, at which point it becomes part of my centered self.
Gleason Sensei and fire/water/heaven/earth mudras: Fascinating question. I see many correlations, including ways that basic aiki principles and concepts lead naturally to the mudras, so that they become an effect of correct movement rather than a cause. There's probably a unified field theory here, showing how aiki, mudras, and kotodama all manifest the same underlying principles. But that's above my pay grade.