Let me preface my remarks by saying Dr. Sears has written a whole book about using soy in the Zone.
But you asked for information or opinions. So
Go here: http://www.westonaprice.org/soy/index.html
Go here: http://www.soyonlineservice.co.nz/
Go here: http://thyroid.about.com/cs/soyinfo/a/soy.htm
Go here: http://www.mercola.com/article/soy/index.htm
Go here: http://www.gi.alaska.edu/ScienceForum/ASF8/856.html
I personally don't and won't use it. I'll go hungry first.
It being goitrogenic, with all it's implications, is all I need to know.
With all due respect for Dr. Sears, this information may not have been available.