Coffee and Caffeine FAQ

I can't do the caffeine thing anymore because even if I miss a small amount - like a coke for lunch - I have withdrawal symtoms like headache, vomiting, lethargy. Its horrible! I have gone clean for about a week at a time, then start up again because I really miss the boost midafternoon. I have heard that yerba mate's chemical composition of caffeine is different enough that you can get the boost of caffeine without the withdrawal problem. Anyone have any thoughts/experience with yerba mate?