I think I would split the difference in terms of what is Frank's and what is KJA's and Brian's.
My guess is Frank wrote an outline and detailed a few things, but it is up to the new guys to fill in the blanks...especially in terms of characterization and tieing it together with their prequel novels.
I mean it seems pretty clear to me that the Great Enemy exemplified in Marty and Daniel were Machines. This was most assuredly Frank's idea. But KJA and Brian made Omnius and Erasmus and the Titans.
I just think we aren't getting Frank's vision necessarily nor are we getting just completely new stuff in these books. I believe it is Frank's ideas through the lens of his son and KJA and they gave the outline dialogue, and characterization, and added some of their own stuff... but that the basic outline is Frank's.
That's my feeling.
You know you are both going to read it regardless. Enjoy the good parts for what it is.