Dadwagon meta-reports that having a kid has mellowed Bode Miller, thus making him either a better skier, a less competitive skier, or both.
I can say that from where I stand, several many rungs down the skiing ability ladder, having a kid has absolutely made me a less frequent skier. But it's also made me a less frequent beachgoer, art fair attender, and a doer of any number of things that involve impulsive travel and/or 3- or 4-day trips.
Want to Be a Better Skier? Have a Kid. Or Maybe, Don't. [dadwagon]