I suggest that you run your own test .
Here are my general suggestions. Others here in the forum are much better informed about hardware specifics.
IME, the location of the Originals (=Masters) makes no appreciable difference in Aperture's performance. My general suggestion remains: Library on the fastest drive (almost always the system drive); Originals on the least expensive drive.
Leave yourself room for your Library and file storage to double in size.
Libraries don't even have to be on the fastest drive. CPU, GPU, RAM, and overall system performance are much more relevant to Aperture performance than Library location.