Good helpful post - you have obviously been doing extensive homework.
Oxidation and chemo and the arguments is not something I have looked at.
There is some information on this site on flax seed, including a some helpful thoughts from a researcher who kindly replied to an email which explains the mechanism of the phytoestrogens in flax seed, and some trials that look at the particular estrogen pathways which for me seem to help throw some light on the flaxseed issue.
On the japanese argument re soy there are so many dietary differences my personal guess is that soy consumption was only part of the factors, and fat intake was probably the biggest cause of differentials. Soy is a whole subject on its own and I have not seen anything that is a clear as the flaxseed research referred to above.
This is the link
http://www.her2support.org/vbulletin...light=flaxseed
And here another
http://www.her2support.org/vbulletin...ight=flax+seed
RB