I don't know if a single screenshot shows much difference, but here goes. (Note that in all of these pictures, I was solely focusing me going up and down, so my reins are too long, and my hands to close to my body, and I couldn't care less about what Phantom was doing as long as she was trotting.)
For video purposes, I did a circle in my "normal" way, then a circle with my leg a bit more under me, then I stood in my stirrups, and afterwards did another circle with my leg where it needed to be when I stood in the sweet spot.
This would be my "normal" posting. It has definitely changed from how I used to ride, and it's nice to see my right leg under me versus in front of me. But I am putting some weight in my stirrups, and using the muscles in my butt to lift me out of the saddle.
On the second circle, I brought my leg back a bit more. It felt like quite a bit more, but as seen in the pictures, it isn't much difference. My heels are up as I am trying to keep from pressing too much weight into my stirrups, but once I find my right spot I do need to work on leveling out my feet again.
Then I stood in the saddle. Note how far back my leg has to be to find the secure position. This blows my mind. Yet if it is at all further forward, I can't keep my balance. I actually should have still been a bit taller here.
But this is the result after standing. It feels so much easier (until my thighs start burning, then it's really hard). I think I look taller (probably wishful thinking on my part). I also think I look super in balance. Not that the other pictures look terribly out of balance, this one just looks solid.
In going through the video in slow-mo to find the above shots, I see that when I sit in the saddle I seem to be closing my hip angle more than I probably should.
But this was mostly what I saw throughout the video:
It just doesn't look as strong to me. I will need to think about keeping my shoulders down and back a bit more, and the feeling of keeping my hip angle open even while sitting. I am trying to get a squatting feeling, but I can't keep it. Once everything starts to click without having to think about it I can also shorten my reins and carry my hands towards the mouth a bit better, and that might help too.
I've given up on ever having a long, elegant position. Short, round thighs that have to get around wide (fat) horses don't lead to elegance. I will settle for a solid, correct position. From looking at the pictures, there isn't much of a difference to the "look", but man, there is a huge difference to the feel.