Installed the progressive springs yesterday, not to difficult with a little creative persuasion. To measure sag I put a wire tie around the upper shock tube, not too tight, just tight enough to stay in place once the lower tube pushes it up. I weight about 215, climbed onto the saddle, feet on pegs, hands on grips, forks didn't even budge. Next, I stood on pegs, hands on grips and shifted my body weight as far forward as possible, sag was maybe 6-7mm. Now I'm kind of scratching my head. Next, on the saddle, hands on grips, feet on ground, bike positioned about 8" from wall, pushed forward with feet and bumped the front wheel against wall, had about 55mm of fork travel. Ok, maybe that doesn't mean a whole lot, but at least I know the springs/forks are doing something.
I'm not completely sure what all this means, but my initial thought is that the springs are too long and the soft end of the spring is far too compressed to be effective. Based on my earlier measurements the soft end of the spring has 26 spaces at 1.85mm width, about 48mm total travel, when installed the soft end of the spring compresses about 50% of it's available travel, my guess is that the remaining 50% of travel takes more force to compress than the first 50% and perhaps a greater amount of force than what is needed for compression of the coarse end of the spring. I suppose I could remove the spring and put it back on the treaded rod and compress it and take some more measurements, but then this really doesn't help to get the length of the spring correct so that there is some amount of sag with rider on the bike.