So moving from 7 to 8 is a 10X difference, moving from 7 to 9 a 100X.
I know you are trying to be helpful, however it is important to be helpful and accurate. Also, I really am not trying to pick on you, it is obvious you have a great desire to be helpful, and you have a fair bit of knowledge too. :D
There are so many variables in pH, that making statements like "your pH will stabilize at...." is a virtual impossibility. What if the substrate is calcite, or silicate sand? Neither of those will have much effect on raising the pH of the tank. What if the OP is a heavy smoker? That will also have an affect on the pH.
It is much preferable to offer advice that is specific and accurate, then it is to generalize an answer using incorrect data.