I have been talking about kamae with a friend for some days now. As he is still getting used to the kamae, which are new to him, he seems to catch on quickly and from starting from scratch has noticed some interesting points....the method of distrubuting the weight 70/30 has a particular feel to it, it causes the hips to spread out and the only way that the kamae can be held is that the hips are open and relatively flexible. With 90/10, one does have to be flexible, but it makes it almost easier because at least the base leg becomes more fixed through the weight. Another thing about the 70/30 way of doing the kamae is that it has a really martial artsy feeling to it- it feels as natural as chinese martial arts or taichi while incorporating a certain martial arts type of feel to it similar to karate kata.
The way i saw it done in the above video seemed to me to be 50/50 sortof like a horsestance except that the hands seemed to form the ichi aspect, i did not really feel the line, so to say. It did look martial through the hands, but the footing seemed more like a halfassed horsestance rather than the legs of someone with open hips that is able to distribute weight really effectively covering ground at the same time. That seems to me to be the point of kamae, to have a solid footing and stance while being able to easily move from place to place in order to attack, avoid(roll..etc. also, someone that is close to the ground in his mindset)
I'm sure any form of kamae is good for various situations, 50/50-70/30 or 90/10 -like the low and firm kamae of the togakurestyle. however, there is something special about the 70/30 because i think it is a great way of training and feels like an accomplishment in itself. When you see the classic ninja stance even in fiction, you often see similar stances also when holding a sword in daijodan- it is a sign of flexibilty and manueverability in of the hips and legs.
j