Soy bvs whey 2.5 years out

I had gastric by pass July 2011 and  have lost all my weight but recently have gained about 10 pounds.   I  need to start getting back to my protein shakes. I am also going through menopause and was advised to up my soy intake.  So, my question is, do you think if I made the change to soy protein instead of just whey that I would be okay? i cant remember why they advocate whey over soy--I think it had something to do with the absorption ?? I would not give up whey all together, just maybe do 3 each a week (sticking with my eggs on Sunday breakfast).

thanks