I think for any normal character movement speeds you shouldn’t need CCD or any special collision detection. I have a public character controller that you can use as a base if you want to try it out. Making a character controller that works solidly can actually be pretty difficult. You run into a lot of unforeseen issues ( I did at least, I guess it was my first character controller 
).
You might want to try that out. I haven’t had any issue getting it not to go through things yet.
Also returning to what you were asking about the physics accuracy, I think that it is pretty much hard-coded at the moment, but it would be an easy fix to make it customizable from the blender interface. I might look into that. Here is the line that loads the simulation step. If I get the time I’ll check to see if I can get it configurable through the interface.