I'm still not sold on this.
The phytoestrogens in soy are so mild they're essentially inert. There are more estrogens in the atmosphere and in plastic containers that are of concern. Some people think that the mild estroens may even work as ANTI-estrogens by occupying receptors. It's all speculation. Besides, RAW soy like tofu contains the most phyto estrogens. In soy isolate it's infintesimal.
Bottom Line: Back in the 60's, prior to Rheo Blair, all protein supplements were made of soy and nobody was getting gyno. To be safe, I'd avoid soy for the most part. It's incomplete protein anyway. But I wouldn't worry about getting a little now and then.