A (small) negative Extra Restart Distance is often useful if the extruder continues to ooze a bit internally. It depends a lot on the temperature & particular material, but it can be helpful to really clean up the seams & such. It probably also depends a lot on the printer & extruder. I use it quite a bit, possibly as much as 50% of the time.
As you can see from the results, getting the ERD just right can be VERY touchy, but it can also make a big difference in overall print quality.
