Can't say I necessarily have more knowledge, but just because you're past peak doesn't mean the engine suddenly stops making power, it just makes less power.
This is why, even though we "peak out" around 8500, some of us are able to get that up into the 9000's and even tickling 10,000. It will keep pulling, it just doesn't pull as hard.
Change the gearing, and all that changes, though. If you go too high, you'll not have enough torque to pull faster or your 1st gear will be too high to be efficient. Go too low and you'll end up with more amazing acceleration, but you will lose top speed.
IMHO, the gearing combo that comes from the factory is nearly spot on for general use. Some like sendler really want a change there because their motives and methods are a little different.
Sorry if I misunderstood the question.