Somewhat off-topic: I realized recently it's more important when and how you get your caffeine then how much. There's a reason 5 o'clock tea is famous. For me morning caffeine is wasted or worse, and the best time is around 3-5 in the afternoon, or a couple of hours after lunch. Metabolisms differ, of course.

Also I switched to black tea: wider spectrum and longer lasting, but smaller punch. Don't abuse it though, may not feel like it but it's as strong as coffee.