In it Nakazono Sensei describes as his training progressed, when he used Kiai strange things started to happen, lightbulbs exploding, large pockets of air forming under the mats which could only be pushed down with ki and not just pushed down with physical strength. Nakazono Sensei describes how he felt that he could have learned to control this power but chose not to pursue it, and outright rejected it.
Cowabunga. That sounds like some sort of acid trip that might have happened in Keith Richards' hotel room. In terms of internal power, I've never heard of such a thing.
Now I am not saying that IP is wrong, or bad, or searching for it is not a potentially good and positive thing to do. I am however questioning that maybe in the broader debate perhaps we are missing something, once somebody has acquired this strength then what, what next?
Next comes old age, your muscles and normal strength atrophy and so you wind up with an investment (IP) that really pays off in terms of quality of life. As Gozo Shioda mentions in "Aikido Shugyo", these things are considered to be an investment for old age. If it was all as powerful as you indicated there wouldn't be any need for techniques, etc.... but since a good and complete martial-art is needed to go with the IP, I'd suggest that the 'power' aspects not be overstated.