Hard to say as I don't closely watch my productivity. It didn't make me significantly less productive, in any event.
edit: And it's nice to feel that I can actually get stuff done without regularly needing coffee.
(Grandparent post is sarcasm, no offense intended.)
I got the sarcasm. <smiles> I am a Brit </smiles>.
I just did not realise not drinking coffee had become cool. Perhaps my age has proofed me from such things.
I don't measure my productivity, I just know I feel better about working when not on coffee and thus work becomes easier. It might be less productive, though I doubt it.
(Grandparent post is sarcasm, no offense intended.)