So I gave some examples of getting under/floating in other threads. Would anyone like to share their experiences in applying this to various waza? What did you notice that changed? Any difficulties?
While I never thought of it this way, I try to apply the general idea or concept of floating to most any force interaction related to waza. Whether I'm receiving the force or outputting it, I try to keep it as low as possible in my body and send it from there. Preferably that's my feet, but that's often times more the goal than the reality
As for what I noticed, everything is just easier. The techniques that stood out to me the most were the ones that involved more force on force interactions when nage was late on their timing. For instance Shomenuchi ikkyo irimi. We normally teach and practice this in a way that nage moves in as soon as uke begins to raise their hand to strike. So that you are catching uke before their force comes at you and then you just push through for the ikkyo. It's more about timing. I found that through maintaining that focus on ground connection through me and by keeping my intent right, the timing didn't matter. Uke would almost bounce off me.
Another technique would be yokomenuchi kata-otoshi. This one is taught similar to the ikkyo above. Where, via timing, you step in to meet the attack before the full force of it is delivered and drive uke back, out from their center and down. Typically we practice it in a way that if timing is right, you go irimi as mentioned above, if not, you receive it and turn away from it, tenkan, and then drop. Just as with ikkyo I found that focusing on the ground connection and intent that timing didn't matter and the choice to finish irimi or tenkan was mine to make. In comparison to how I'd always done this technique and seen it done, it was completely effortless and my uke commented that it felt like running into a brick wall at the shoulder. One other thing that I noticed was that whether I finished irimi or tenkan, the technique was done exactly the same. Typically when someone is late and they step back they end up grabbing gi and pushing down on the shoulder, almost like some sort of arm drag rather than something that resembles the way the irimi version is done. When doing it the way I mentioned above, nothing changed, once uke was up what happened from there was up to me, but the technique didn't change.
Beyond those two examples, I think any technique where you end up, either on purpose or by accident coming up against uke's force or weight, the difference is pretty noticeable as you don't get pinned down or off balanced as easily.