Yeah, anything stronger than coffee is unchartered territory for me, I just don't know how my body will react. A Friend of mine had a bad experience on similiar supps and had to go to hospital due to his heart beating too fast. I can see the appeal though, if I knew I would be fine on them then I would take the dive.
Must have been some sort of medical reaction?
I can't imagine any legal substance would have that effect on all but a very small % of people.
But then if coffee does the trick then there is no need for anything else.