I didn't know flax seed oil had anything to do w/ estrogen. Some products like soy that do have weak estrogens can theoretically be beneficial since they are weak estrogens that bind to the receptors and not allowing the stronger estrogens to bind if you take prohormones or roids. But i never heard of flax being associated w/ estrogen in any way. Personally i think Flax Seed Oil (or another source of Omega 3's) is a necessity.
I have just heard that the lignans in flax oil have anti-estrogenic effects, in the ways you mentioned. So, I was wondering if I should avoid buying high-lignan flax oil, and just buy the one that is not labeled 'high-lignan'.