Not the balancing per se, but the design of the balancing and how it works out with that particular casting. That hole is there for balance reasons and is pretty big; the long stroke forces it to be bigger for balance reasons. So the casting section is thinned out there a lot as a result. The 340 forged cranks had the same hole drilled, and for the same reason, but it was not as large and the whole crank around that area was thicker and had better slopes and strength in the area around that hole.
