I don't really see the point of giving up caffeine. Sure, if you're one of those people who absorbs it much more quickly then it might be worth it, because you're likely to have a caffeine-related energy crash more rapidly too, or if you're having five or six cups a day and feeling awful as a result.
I'm trying to cut out all added sugar from my diet, so things like fizzy drinks, crisps, chocolate, sweets, cakes, etc. I noticed recently that if I have too much sugar in a short space of time, I experience a massive crash as a result. It's much more noticeable than a bit of caffeine so I decided to see if I'd feel any better if I cut out all added sugars.