Caffeine does nothing for me, I drink it for the taste / force of habit, and can actually cut it out indefinitely. Yes, I also have adhd.
As others in this thread have mentioned, the taste of coffee is just too good to give up for me. Instead, I limit myself to: 1) 2 cups of coffee a day before 12pm, 2) allow myself to drink decaf after 12pm
I also allow myself to become caffeinated if I have to drive in the dark for long periods at end (e.g. 2+ hours). These moments are rare enough for me to make caffeine one hell of a drug ;-)