I don't know why people say dumb things such as "all the competitive players still play 1.6" because if people weren't competitive there wouldn't be leagues and in general no one would play. It's not like some team game where you go and say "Hey guys, I'm gonna get killed 500 times in a row for the team because it's fun and I'm not competitive!" 1.6 has a better map selection and better FPS, but who needs 100 FPS when the graphics look terrible compared to what's out there. The boxes in Source USED to be better than 1.6 too, until they updated that once it was officially released.
I haven't played 1.6 hardly at all since all my friends got Source. Maybe put in 2 hours since November.