Marcus touched on a few things I'll comment on.
As I see it, there are stance pairs (shown somewhat above) which are complimentary. These would be the following
Sanchin dachi vs. Renoji dachi
Heiko dachi vs. Hachiji dachi
Kiba dachi vs. Shiko dachi
Look on your charts above. What you will notice is the difference between the stance on the left vs. the one on the right is a 30-degree rotation of the femur in the hip socket. That's all.
In my view, it's all about cocking a torsion spring in the hips. I've learned to use that spring (along with compression and flexion springs) to store and release energy for kicks and thrusts. In particular, I find that Sanchin allows one to throw a powerful whipping kick off the front leg by storing energy in the leg torsion springs. You can't do that from the relaxed renoji dachi.
Kiba dachi creates firmness of stance which I find useful for doing hip throws, or skating confidently across a slippery floor. Shiko dachi tends to be something I go to when exploding forward.
In my view, Uechi's horse stance can be variations of the kiba dachi, shiko dachi, and something more Chinese. I see George doing this more frontal Chinese deep stance in his forms. I also saw Simon doing that in the Fuzhou Suparinpei after coming back from China. In the classic kiba or shiko dachi, the navel would be slightly off to the side. In the frontal horse stance, the navel would face the target (along with the pelvis) and the back knee is a little more facing forwards than out.
In the following Sanseiryu sequence...
- Double boshiken
- Gedan barai
- Shoken sukuiage uke
- Double shoken toss
... I now shift from one variation of deep stance to another. I've got a kiba dachi, a zenkutsu dachi, and a more frontal Chinese horse stance. I'm actually very comfortable shifting amongst these different deep stance versions because I learned how to in the Yang style Tai Chi short form.
I hope all that makes sense. Basically what I'm saying is my classic line - it's all good. Not only is it all good, but I think the real secret to hip-driven power is in the transitions between the variations.