I know I said that I wouldn't visit the forums till 9/22/10 but I'm an *** and I had a theory that I would like people to test when Open Beta begins.
At current everyone speculates that the exp over an 8 hour period diminishes and that eventually you will get 0 exp.
I do not believe this to be the correct way of thinking as this is called a “Surplus Exp” meaning that you have an excess amount. This can possibly mean that at current you are getting more than regular amounts of exp. This is to assist in the casual gamers because their exp is very low. This would be the equivalent to using the exp ring in FFXI.
It would make sense that this would diminish over time to hardcore players. The system was designed to help out casual players so as a hardcore player it would make sense that you would hit that cap quicker and just receive regular exp instead of surplus exp.
The only way to test this is to have hardcore gamers pull an 8 hour shift to see the percentage loss of exp at every hour. You would be documenting all your experience gained at every mob for 1 hour. At the top of every hour you will take the average of the experience and then repeat every hour. This is the only definitive way of testing out the surplus exp system.