Interested too.
DS has been on soya milk for a long time (about 2yrs now). I put him on it myself as I was getting no help whatsoever from the GP when I suspected a cow's milk intolerance. When the HV found out he was on it several months later she did say that GPs dont like it, but that if it suits DS I should stick with it and go with my 'mummy instinct'. She didnt give any reasons why the GPs dont like it, certainly didnt mention anything like this, and didnt seem to think there was a problem with him staying on it.