The option of the source code with Eclipse is useful mostly for testing and helps make other changes to the program.
I would keep the slider 4 position for predefined qualities:
- Q1 : overview of 3D view with shading
- Q2 (low) : globalIllumination = default, diffusedBounces = 1
- Q3 (medium) : diffusedBounces = 0
- Q4 (high) : globalIllumination = path, diffusedBounces >= 1
I will deal with the option of plug-in in depth for usual use.