TheBlade 3 or so years ago I did the Mizuno Shaft Optimizer test gizmo. It recommended Modus 105 R flex. I was able to demo a set of Mizunos. The shaft had a strong ballflight. I liked the mid irons but found the short irons to feel heavy and stiff. I think I'm more used to unitized shafts, meaning the ones that come as all 41 inches, and then you tip each iron differently. That makes the short shafts actually lighter than the longer iron shafts. And the flex curve is usually softer. So what I'm saying is take my review with a grain of salt.
I think the 105 is sort of a light Dynamic Gold kind of shaft.