Respectfully, FredWyn...there are more than two camps than either those who laud Vickers...or Yeager, (of which there don't seem to be many around these parts). Stick around here for a while, read the threads and the thoughtful comments and you'll find that out for yourself.
Personally, I take good information where I find it. I'm not a cult of personality kind of guy...and I've trained with some pretty "been there / done that" sorts myself over the years, especially when I was on SRT. That meant SEALS, GSG9, SAS etc. But that's beside the point.
None of that necessarily makes me an expert, in fact I know I'm not one. And for that matter, your credentials as an author and an educator do not make you one...at least not in this particular field. There are plenty of authors and educators, some here even, and most do not qualify as experts nor any more capable of evaluating the expertise of a particular trainer or SME.
If credibility on this site matters to you, take your time learning the personae dramatis and don't throw the baby out with the bath water.
We value good information here...especially when it comes from a credible source.