The interesting results from the TW Professor's string spin research showed that spin can be increased by increasing the freedom for the mains to travel laterally within the plane of the stringbed (by using a 16x10 pattern). However, the 16x10 pattern was much more effective when strung at 60 lbs vs 30 lbs. It was shown that a soft stringbed allows the the ball to "dent" the stringbed more, resulting in normal forces on the bottom of the ball that increase launch angle and reduce the spin potential.
The take-home result is that a stringbed with freedom for string-on-string sliding combined with high stiffness leads to maximum spin. Unfortunately, a 16x10 pattern cannot practically be strung tight enough to take advantage. But there are ways to apply the physics principles in a more practical approach.
A typical modern poly or poly-hybrid stringbed is quite effective for producing a good combination of spin and power. However, the tradeoff (compared to the less spin-friendly stringbeds of the past) is a higher launch angle that makes it more difficult to control the rebound angle off the racquetface for heavily spun incoming balls.
Stringing a poly stringbed much tighter to make it much stiffer (or using a denser stringbed) reduces the launch angle to give better directional control, but at a cost of reduced spin and power.
Fortunately, there is a way to combine the advantages of a typical poly stringbed (good spin and power) with the enhanced control of a lower launch angle. The key is to string the racquet in a way so that the center portion of the stringbed (where the ball impacts the strings) is extremely stiff, to prevent the ball from denting the stringbed, while making the peripheral region of the stringbed extremely flexible to allow the ball impact to stretch the edge of the stringbed to increase the deflection of the center. An easy way to do this is to string the racquet 10+ lbs tighter than normal, but then skip the outermost strings); e.g., converting a 16x19 pattern into a 14x18, or an 18x20 into a 16x18 or 14x18.
I have applied the latter technique to my RDS001MP, to amazing effect. In fact, I have found that the spin level of my 14x18 pattern RDS strung at 70 lbs far exceeds what I can generate at 53 lbs tension with the full 16x19 pattern. Even with the extra spin potential, the stiff center of the stringbed makes the racquet much more accurate on volleys than with lower tensions too.
The effects of the 3 cases mentioned above are sketched below: