Shear tests are [in my opinion] senseless. The shear stress you measure depends more on the shear rate and on the point where the force is applied than on the grain structure. When shearing a component, you not only apply shear stress, but also roll the component over. This means that shear stress and normal stress are present, again making the results very dependent on where you apply the load.
Properly wetted solder joints have ample strength for anything happening to them (with the exception of single-sided PTH), and there is no correlation between shear (or pull) strength test results and fatigue reliability.