The tea would stain the same amount as coffee or ordinay tea.
I drink around 4-5 Cups a day and have not noticed any staining.
The benfits on drinking the tea or tablet can depend on what you are putting in the tea. If you add sugar, to make it taste better then the tablet may be the go. (be wary of the pre-mixed tea - They contain a very large amount of sugar and sweeteners)
Drinking plane green tea, can also aid in your daily water intake.