I picked up an Edge-On-Up cutting edge tester the other day and have been playing with it the last couple of days. I'm not sure how applicable the test results are to woodworking but....It is nice to have quantifiable numbers relating to how sharp an edge is, to be able to say off the stones it takes x grams of force to cut the test string and if I strop that force is y less. While more testing will be needed, early results indicate stropping on hard leather with 'green stuff' will lessen the force needed to cut the test string by about 50 or so grams vs straight off the stones. Two other interesting results are stones do not make a testable difference, I've A&B using Spyderco, Ark Translucent, and Shapton 8000 glass, there is not a measurable difference between any of the three when sharpening O-1 iron. The other is freehand vs. Jig, there is also little difference, if any freehand has needed less force than using the jig but the difference is so small as to be easily in the margin of error.
More fun with cutting strings to follow,
ken