You know, I've cut caffeine from my daily diet these days due to concerns about my heart, and I could hardly manage any at all to begin with, let alone the kind of caffeine you get from coffee... But last year when at cons, I used to drink Diet Coke non-decaf to keep myself awake during the daytime instead of the nighttime. And I usually found myself awake, but kind of feeling unpleasant, and eventually I would either get chest pains if I had too much, or an urge to go to bed at 6pm if I didn't have enough.

Then before one con, we randomly picked up that Ocean Spray "Cranergy" stuff, cranberry juice with green tea extract and stuff to turn it into an energy drink. And there were no crashes, and no chest pains, and I had the urge to go to bed at a normal hour - and when I did, I could sleep. It was awesome.

So I'm inclined to think that tea delivers caffeine better in general.