Re: What is "IT"?
I am an engineer by education as well as occupation. My understanding of engineering concepts has done little to further my progress of developing "it" nor recognizing when others possess "it".
Only hands on time with people recognized in having it and a lot of solo training has develop any understanding of "it" and when others possess some variation of "it." The Aunkai in tokyo has more than a few members with science/engineering degrees all the way up to the PhD level and I am fairly certain they would agree with my opinion.
A more productive discussion of what is it and what isn't would center around where we do see movement in uke/tori and where we don't, what it feels like etc rather than describing the mechanics.