Yes, I have benefitted tremendously from quitting regular caffeine intake.
I used to drink a cup or two every morning, and get extremely tired in the afternoons. Even if I drank more coffee in the afternoon, (which I often did) it didn't affect my tiredness.
Once I quit caffeine, this stopped. My completely non-scientific, but probably close enough, explanation is that the caffeine was somehow causing me to "burn out" my energy stores and to use them all up in the morning, leaving me low-energy the rest of the day. So now my energy is much more even and I have higher energy throughout the day (though it takes me longer to fully wake up).
I still drink decaf for the delicious ritual of it.
I also sometimes drink caf -- I just make sure not to do so regularly enough that I get habituated to it.
As a side benefit, when I drink a SMALL amount of caf now -- say 1/3 of a cup -- it gives me a great, jitter-free energy boost. This didn't happen when I was a coffee regular. It's actually quite useful at times. (I don't get the downside, the afternoon tiredness, until my body becomes habituated to caffeine).
On cold turkey: if I do this, I get a terrible headache and become so tired as to be useless for about a day. I much prefer to phase the caffeine out over a week or so -- no negative effects that way. Some people can go cold turkey just fine though.