You can hit all manner of objects while being relaxed as well as using the hips and a weight drop. Its pretty "heavy" compared to when people muscle things, but it isn't the same thing as IS/IP etc. It is probably the best one can use when using "external" strength, and shouldn't be taken lightly, but has short comings compared to the stuff others are talking about.
That is what intrigues me so much about your experience of it. Especially Dan's.
I have not, nor will I ever (en sha'allah), judge something or someone who is kind enough to teach me something.
Dr. Shie Ming Hwang (rather well respected fellow I understand in Taiwanese Kung Fu ranks) recently shares the training program he used to make his son so good. Was it the whole program? Likely not. He and I were feeling each other out for about two years (I travel allot). But his stuff was magnificent and I honor him for sharing with me what he did.
I have done similarly since 1971. And what I learn from IS/IP when that happens, will be treated just as honorably. And I will honor those who shared it with me.
My learning is never stagnant. And my theories and concepts are "beliefs" that are subject to refinement or 180 degree change.
I do not set myself up as a teacher or as a leader, I am simply sharing my experience freely in hopes of raising discussion among people of similar interest. And I am elated when the discussions open doors to meet folks.