I can do this, but I'm not sure if I would meet your qualifications. I'm not trying to be a jerk here, but again if the same result can be achieved, I don't know what else to look for.
On something like this, would your argument be that IP people would be less fatigued than an athlete doing the same thing? Or simply that you are interested in a specific quality personally?
Again, effortless seems a bit subjective. What is effortless for one might not be effortless for another even though they are using the same means. For example, If I can easily bench 400lbs, and you can only bench 200lbs, benching 175 might be effortless for me, and I could do many many reps, for you it would be very near max, and take a lot of effort. I understand what you are saying, but I feel that "effortless" is a very personal thing.
I think you might have recognized something there.
There is a specific quality/feeling/sensation that we are all looking for.
That is to say, that to most people looking from the outside, wether someone uses internals or externals to power something it looks the same, but to both people it feels substantially different. This is why I hesitate to call one way better than the other if the same results are achieved. Now if you have a little bit of experience with internals, and you watch you might be able to tell how each movement was powered between the athletic person and IS powered person. Likewise, the effects on the partner might look different.
I understand your point regarding strength and how "effortlessness" can be subjective. If you decide to chase after this feeling/mode of movement, the feeling of it being effortless is really just that. For example, if I raise my arms with no one pushing on them, then I raise my arms with someone holding on to them utilizing IS for both raises, it really doesn't feel any different to me. My arms kind of just float upwards as though something else was raising them other than my shoulders. To the person who is holding my arms, they don't feel me lifting them up at all. What feels strange to them is that they do not feel any resistance, they can't really tell where I am sourcing my power from.
The wacky thing is that when I do conditoining exercises now, my shoulders don't really get tired like I used too, instead other parts of my body start to get tired and from my experienced this shifts lower and lower the more skilled/conditioned you get.
Now to get back to your original question in your first post, the way in which this may be "better" is that the athletic person may not have experienced this sort of thing before so you have that element of surprise/unreadability coupled with being able to generate power from unusual positions in which others might be seriously compromised.