The bottom line with this frame appears to be......if the strings are not notching, then this frame is probably not giving you the extra spin (as the mains arent constantly sliding back and forth.). I think the best we can do is limit friction between strings to extend stringbed life.
Now, if one hits flatter, then such notching is not going to be as bad. But, as many have posted, this frame is probably not a good fit for a flat hitter. Personally, I cant flatten a ball out to save my life so this frame is a good fit.