Check out the following charts at zknives:
http://zknives.com/knives/steels/steelgraph.php?nm=r2%2C+sg2&sz=2&gm=0&hrn=1
http://zknives.com/knives/steels/steelgraph.php?nm=SRS-15%2CSG2
The first has Kobelco Steel R2 versus GSB Acero R2
The second had Takefu SG2 versus SRS-15.
If...