One more, in light of the new nerfs, already put it on Mantis:
Identical setup to earlier tests but under 4.057, cumulative results (.053/.054/.055/.057):
Path 1: III's 9/7/7/5, II's 4/4/4/4, I's 3/3/3/3
Path 2: III's 6/6/6/5, II's 4/4/4/4, I's 2/2/3/2
Path 3: III's 8/7/5/5, II's 4/4/4/4, I's 3/3/3/2
Path 4: III's 10/7/5/4
Path 5: III's 10/8/6/5
Averages: III's 8.6/7/5.8/4.8, II's 4/4/4/4, I's 2.7/2.7/3/2.7
Again, keep in mind all these tests are from a homeworld, so the first world is "free" in that it doesn't have a tachyon guardian. By the standards I've been using we've now seen a 44% drop in Mark III performance since 4.053, but if we account for that free world it's really more like 50%.
I was actually surprised to see another scout nerf in .056, I kind of thought you already had it about right in the last patch, maybe even towards the harsher end of the "good" range.