I don't know where you heard that, but these two Dr.'s disagree and they're pretty prominent on blood type research. I have seen nothing on curezone about that either.
Westsoy is the sh*t, if you get the unsweetened organic kind. They might not carry it in your area, but if they do I'd go with that.
If they don't, then first look for any soymilk that is organic. That will make sure that it's not genetically modified. Always check the ingredients though, they always put extra junk in that is bad for you.