El Mahdi
Muad'Dib of the Anauroch
What extra tracking do you refer to? I don't think there is any in the proposal.
Checking if my hit points went under my constitution score is no different from checking if they went below zero.
But you do need to list and remain aware of that threshold. Either by having it marked somehow in the Hit Point area of your character sheet, listed seperately, or just remember it in the main hard drive (one's brain).
Zero is Zero. It's the same for every character and therefore something quite instinctive. Using Constitution/Fortitude however means the number is different for each character. May not seem to be a problem to you, I also don't view it as a problem.
I'll admit it's a very small thing to keep track of, and I would have absolutely not problem with it. But others find anything extra they need to keep track of, even as minor as this, as one thing too many to track. May not seem to be a problem to you, I also don't view it as a problem...but trust me, there are a significant amount of people who won't like it simply for this aspect.