Does the separation of the differential pair shielding of a SATA cable matter?
Yes the conductor width to gnd gap and gap to adjacent pair is critical as this determines both incremental capacitance and inductance but the L/C ratio affects the controlled impedance which in turn affects return loss, and amount of cross talk.  

The SATA 6GHz  cables were stiffened in design to improve DC to 6GHz controlled impedance variations due to bending and retain these critical dimensions of conductor thickness to gap ratio and dielectric constant of the insulation, as well as loss tangent of the dielectric at GHz frequencies.  The connector is also equally important in geometry.