I was going to add a diffraction aware feature to DOFIS at a later date, but realised it was so easy to do, that I might as well add it now.
The diffraction awareness in DOFIS means that it will use the ML set CoC as the total blur, and thus, use diffraction to calculate the required defocus blurs, for the depth of field. You can see what the defocus blur is at the near and far DoFs by accessing the additional info in the DOFIS menu.
The DOFIS menu now looks like this:
If diffraction aware is set on and the aperture is too high, DOFIS will warn you.
If you put diffraction aware on, you can dynamically find the sweet spot from a DoF perspective, ie maximum DoF that satisfies your total blur need.
DOFIS alerts you to whether diffraction awareness is on by displaying a + in the DOFIS LV window, rather than a - for diffraction off.
BTW the front principal position, relative to the sensor plane, is shown above, at 114mm.
I believe DOFIS is now maxed out with features, but I will always entertain ideas if you have any.