The reason you need the libraries (.so) files:
The kernel has an interface that allows programs to control it's minimum and maximum speeds among other things.
These libraries look for certain things you are doing with the device like LCD off or touch input, and varies the clock depending on those activities.
The problem is, the libraries are hardcoded for the stock clock speeds, so even if you limit the speed to something higher like 1.83, the library quickly overrides it back down to 1566. This is likely why your benchmarks are very similar.
I have modified the included libraries to eliminate this behavior. When I get the GUI app done there will be an option available to modify the libraries for you, I will also include them with the kernel in a CWM zip when we get CWM up.
That should answer the question of what "taking full advantage" means.
Also note that the PLL used in our device to source the clock speeds is rated at 1.72GHz. So 1.83GHz is a fair bit over it's design, could be why we can't go higher.
