Also quit coffee to switch exclusively to green tea. I was just getting too much anxiety. I definitely feel much calmer without coffee. In general for I think I was a great move, I work a little less, but when I work it tends to be on more relevant things.

I'll typically have one cup of coffee one day on the weekend, especially if I'm going to do something to burn the energy (hiking/biking).

EDIT: technically not a programmer but a grad student in a computational field, but I think it's very similar work mentally