I would suggest that anyone concerned about of their edge finding method run an R &R test.
Repeatability: make multiple approaches to the edge and note the position with a tenths reading DRO, dial indicator, or test indicator.
Accuracy: find the opposite edges of a reference block, noting the difference in position with a tenths reading DRO. Measure the reference block with a known good micrometer and compare. This test would be more difficult without a DRO as position would depend on the accuracy of the lead screw, the ability to accurately read the dial to a tenth of a thousandth, and would have to take backlash in the lead screw into account.
I ran an R & R study this morning using my mill. I mounted a 1-2-3 block on the table and swept the 3" face to verify that is was parallel to the y axis within .0005" I zeroed the DRO in both y and z to ensure that I could return to those settings. I then ran the edge finder to the left side of the block and zeroed the x axis. I was able to return to the exact same reading on multiple approaches. Readability to .0002" (the resolution of the DRO) confirmed.
Next, I lifted the edge finder to clear the block and approached the opposite side. I approached multiple times, again verifying repeatability. My reading was 2.4998". Subtracting the .5" edge finder tip diameter., the distance across the block was 1.9998". Finally, I measured the the 1-2-3 block at the contact point at 2.0000" with two different micrometers. This amounted to a difference of .0002" or .0001" per side. The Accuracy confirmed.
In my experience, several considerations are in order when using an edge finder. The edge finder contact surface and the surface of the edge being found should be clean and smooth. An oil or coolant coating will will create a film which will create drag on the edge finder tip and cause a premature jump. I use a contact length of about 1/8" rather than exposing the entire tip surface. When center finding using opposite edges, I make sure to use the same contact length. I use around 700 - 800 rpm for spindle speed. I also use a very light coat of oil between the tip and the shank of the edge finder. I apply a droplet of oil to one surface and wipe it off, removing most of the oil. I find the this gives more consistent jumps. Erratic movement of the tip is a good indicator of the need for lubrication. I set the preload on the spring at about 2 lbs. n My edge finder of choice (I have two full sets of them) is a 1/2" one that I bought from Enco or Travers maybe thirty five years ago. I prefer the 1/2" to the .200"; I think that it gives a crisper jump. The larger radius means that less drag force will be required to make the jump.