Imperial Hubris was written later, and, in it, Scheuer contradicts some of his points in Through Our Enemies' Eyes, claiming that he had gotten it wrong in the first book. Given that the second book is more of an attack on Bush, some skeptics suspect that facts in the first book got in the way of arguments in the second, so the facts had to be denied. Unfornately, I've forgotten what was at issue here. So, Scheuer has an agenda. I would rank him high above Richard Clarke, but then Clarke's reputation for veracity ranks only slightly higher than Clintons, IMHO.
Thanks for all of that information.