It's definitely bad for teeth, I would dilute it as other mothers have suggested. Have you researched the soymilk thing as well? It is pretty controversial. I know its soymilk you are giving here, but here is some info about soy formula that should be pretty similar
Birth Control Pills For Babies
But it was the isoflavones in infant formula that gave the Jameses the most cause for concern. In 1998, investigators reported that the daily exposure of infants to isoflavones in soy infant formula is 6 to11 times higher on a body-weight basis than the dose that has hormonal effects in adults consuming soy foods. Circulating concentrations of isoflavones in infants fed soy-based formula were 13,000 to 22,000 times higher than plasma estradiol concentrations in infants on cow's milk formula.57
Approximately 25 per cent of bottle-fed children in the US receive soy-based formula - a much higher percentage than in other parts of the Western world. Fitzpatrick estimated that an infant exclusively fed soy formula receives the estrogenic equivalent (based on body weight) of at least five birth control pills per day.58 By contrast, almost no phytoestrogens have been detected in dairy-based infant formula or in human milk, even when the mother consumes soy products.
Scientists have known for years that soy-based formula can cause thyroid problems in babies. But what are the effects of soy products on the hormonal development of the infant, both male and female?
Male infants undergo a "testosterone surge" during the first few months of life, when testosterone levels may be as high as those of an adult male. During this period, the infant is programmed to express male characteristics after puberty, not only in the development of his sexual organs and other masculine physical traits, but also in setting patterns in the brain characteristic of male behavior. In monkeys, deficiency of male hormones impairs the development of spatial perception (which, in humans, is normally more acute in men than in women), of learning ability and of visual discrimination tasks (such as would be required for reading).59 It goes without saying that future patterns of sexual orientation may also be influenced by the early hormonal environment. Male children exposed during gestation to diethylstilbestrol (DES), a synthetic estrogen that has effects on animals similar to those of phytoestrogens from soy, had testes smaller than normal on manturation.60
Learning disabilities, especially in male children, have reached epidemic proportions. Soy infant feeding - which began in earnest in the early 1970s - cannot be ignored as a probable cause for these tragic developments.
As for girls, an alarming number are entering puberty much earlier than normal, according to a recent study reported in the journal Pediatrics.61 Investigators found that one per cent of all girls now show signs of puberty, such as breast development or pubic hair, before the age of three; by age eight, 14.7 per cent of white girls and almost 50 per cent of African-American girls have one or both of these characteristics.
New data indicate that environmental estrogens such as PCBs and DDE (a breakdown product of DDT) may cause early sexual development in girls.62 In the 1986 Puerto Rico Premature Thelarche study, the most significant dietary association with premature sexual development was not chicken - as reported in the press - but soy infant formula.63
The consequences of this truncated childhood are tragic. Young girls with mature bodies must cope with feelings and urges that most children are not well-equipped to handle. And early maturation in girls is frequently a harbinger for problems with the reproductive system later in life, including failure to menstruate, infertility and breast cancer.
Parents who have contacted the Jameses recount other problems associated with children of both sexes who were fed soy-based formula, including extreme emotional behavior, asthma, immune system problems, pituitary insufficiency, thyroid disorders and irritable bowel syndrome - the same endocrine and digestive havoc that afflicted the Jameses' parrots.
It's taken from http://www.mercola.com/2000/apr/9/soy_research_update.htm
I would research it if I were you.
I know you have made up your mind about soy, but here is some info I came acrossed that I found interesting. BTW I do agree with you about cow's milk too, at least when it is not organic or raw. http://www.mothering.com/articles/growing_child/food/soy_...