Some points that you may want to consider in this discussion. Birth rates are directly related to both life expectancy and education. Therefore in an Extropian future in which both of these qualities are more abundant the population problem may be a nonissue. In the Western countries (U.S., Canada, Western Europe) population growth is negative if one discounts immigration. This wealth-education effect has been confirmed in developing countries as well. Numerous children serve as cheap labor/social security in poor countries. As the wealth increases the benefits of the tradeoff of current for future resources shrinks and the number of offspring does likewise. Humanity is able to look to the future and make decisions based on personal benefit. This reasoning ability counters the tendency to breed indiscriminately.
The current projections of the United Nations predict a leveling off of global population by the mid 21st century with a high estimate of I believe 18 billion. Birthrates are slowing around the globe which is a fact that an alarmist media continues to overlook. The media would rather play up Cassandra predictions like those of Paul Ehrlich who has been consistently wrong since the Club of Rome predictions in the early 1970's.
I am surprised that Julian Simon has not been mentioned yet.