I've given up assuming on string patterns - I think they combine with all the characteristics of the frame to produce a certain behavior. If you were to play two of the same model of frame, one with an open pattern, the other with a dense setup, I'd expect the open pattern to have a little more spin potential and maybe a little more pop while the dense pattern would probably have a more even response.
One of the easiest racquets for me to produce spin with is the Prince NXG mid which has one of the densest patterns I've ever seen, but it's also hefty and reeeeally soft. My old Prostaff 6.1 Classics have an open pattern and are pretty stiff, so they put a lot of punch on the ball, but I have trouble hitting them with enough spin to keep the ball down on the court. The weight, balance, headsize, and flex of a specific frame all have a big impact on how it will perform. While the type of string pattern can be included in the performance conversation, I really don't worry about it as much as the other aspects of a racquet's construction.