A few of the roadies I ride with have gone tubeless. Flats have been VERY rare for them (like 1 or 2 a year, in thousands and thousands of miles), though if you do flat, and you want to put in a tube to continue your ride, you have to be careful to clear out any debris that have accumulated on the inside of the tire or you'll immediately flat once again.

I plan to convert my "fast" bike to tubeless, but will probably stick with a regular clincher/tube set-up for my commuter (28mm Ruffy Tuffy tires have proven quite durable for me).