It would be like playing a passage with "fast legato" and slowing it down, you're not going to get the proper articulation for it, and another thing by doing that you'll constantly end up with the same articulation, thus the same sound through out all your runs no matter what speed they are played, that will sound so machine like.
The real solution will be more complex than that or involve a lot of runs at various speeds sampled. There's nothing free in life....
The real solution will be more complex than that or involve a lot of runs at various speeds sampled. There's nothing free in life....