Claims can be cross-referenced, chronology can be checked and logic can be applied.
I really like this sentence, to which I would add, " and we would still never be certain what really went on."
As you likely are very aware of, the Hombu vs. Iwama attitude was and still is very strong. I believe that Chiba Sensei was playing into that. My claims are just that, mine and I certainly understand that others are going to have different ideas. My claims are based on cross-referencing other's claims and applying logic. I attended the 70 year anniversary gasshuku and was able to practice with and talk to a few old timers as well as listening to the many speeches.
My logic application comes from my years of living in a community very much like Iwama as part of a farming family stretching back 18 generations (at least that is what my grandfather-in-law claims!). For example, I do not believe that many full time farmers would have had the time to train in any serious matter.
As an example of the locals' attitude, there is an interview with Saito Sensei and how he first encountered O'Sensei. He says something like hearing about this strange old man. Everything thing else I have heard as well as applying my own experience jives with this.
I do believe that Iwama has produced some excellent, wonderful Aikidoka. (Inagaki Sensei, in particular, was very kind to me.) I also believe that Iwama has a certain reputation to live up to and that many of these individuals had a part in making it as well as continuing it, even if certain truths have to be altered a bit.