I've seen similar results in terms of no major loss of alertness and no fogginess, but I definitely get frazzled nerves, mild headaches, etc, when I stop drinking tea/coffee/etc.

The problem for me is on the other end. After spending more than a year off, going /back/ to drinking caffeinated drinks caused me far worse issues - complete insomnia, with the accompanying issues related to lack of sleep. My mind simply doesn't shut down at night if I regularly have 1-2 caffeinated drinks a day for the span of a week.

So while breaking myself isn't too bad, going back to drinking caffeine in any regular quantity is TOUGH, and not something I care to try again (after three trys).