Sure, I am fine with this.
I will even go further - I know of some who understand it but refuse to teach it.
Sure, ever heard of Sokaku Takeda?
Anyway, there have been quite a few definitions of IP/IS over the years, if you search through the forums. There's also a pretty good summary at http://www.internalartsinternational...-internal-art/
For "It has to be felt" - well, it's pretty had to teach anything in a detailed manner by correspondance - try doing it with conventional Aikido and you run into the same problems. The more subtle and complex the skill the harder it is.