NO! I say that emphatically b/c I completely disagree with messing with nature like that. I know a couple that did the sperm spinning deal to guarantee the sex - they wanted a boy. They had a girl. Then, within less than a year, she was pregnant unexpectedly and then they had a boy. I told her that was God's way of saying He is still in control, no matter how advanced we become with medical technology.
While I would have liked one boy and one girl, I have always maintained the mindset that a healthy baby was more important and I feel blessed that God has given me the honor of being a parent.