Does a profit on bow sight scale mark correspond to a speed profit when we compare two limbs pairs ?
Not necessarily: the bow sight scale mark depends primarily on the archer's morphology and the position of the nock point compared to the riser with the maximum draw length.
According to the way in which the two limbs top and bottom work, the height of this nock locator may vary.
None of the traditional adjustments (brace height, tiller) are made at the maximum draw length, so there is no reason that the nock point height will be the same when at maximum draw length.
To do a comparative speed test, we know of two methods:
Use a chronograph.
Compare the bow sight scale mark at 70m and at 10m: the smaller the variation, the higher the speed.