Additional testing needs to be done but the new PCB seems to perform as well as the previous one - i.e. better than 1 milliohm results all the way down to zero. Some tweaking needs to be done on the high range since I don't have the required multi-turn potentiometer. A typo was found on the schematic that needs to be fixed.
There is a known problem where occasional instability occurs when measuring resistances below 20 milliohms. It has been hypothesized this could be corrected with additional capacitance / diode protection and footprints have been provided on the PCB to experiment further. Once testing is complete the schematic will be updated as needed. I plan to put everything on github and provide a link. I have a limited number of extra PCBs that I will share with active element14 members who are interested.
Longer range it would be nice to have automatic range selection and consistent display units. This could be done with a microcontroller and the board provides sufficient access to allow prototyping.
I need to put it in a nice enclosure :-)