I don't think we are at the point where we can adequately assess the risks involved. It's known that higher IQ is correlated with major depression, bipolar disorder, and schizophrenia. What use is having a super-intelligent child if they have to spend most of their teenage and early adult years away from society, in a medicated stupor?

There may also be other genetic side effects to increased intelligence, such as increased risk of alcohol dependence and substance abuse.

I think I remember a study saying that over an IQ of 130, there is no correlation between increased intelligence and success/happiness.

It would probably be far more worthwhile to focus on having children of moderate-to-high IQ score (120-130 range), and put more emphasis on better upbringing, instilling values such as the importance of socializing and putting effort into one's goals. The focus that some transhumanists seem to have on raw intelligence seems a bit childish and naive.