Allowing a user to say I want 50,000 inserts per second, as opposed to playing with the number of threads and workers to achieve that would be a really nice way to polish the tools. This way we can do a ramp up to the speed we want to be at at consistently without our users needing to run custom testing to configure the loader for every environment.
This is clearly tricky in a few ways as an upper bound is easier to enforce than a lower bound. For example if someone can't achieve 50,000 on their hardware, they will go as fast they can go to get as close to it as they can. But it is much more difficult to say I want to go faster than X because that will depend on many factors.