I recently ran across a second hand PRS custom that has 3 factory Duncan p-90s and a 5-way switch (not sure which model p-90, is there a way to tell?) Please compare/ contrast this set-up with the more common dual humbucker set-up. What are the advantages/ disadvantages? If I'm interested in a hard rock/metal tone would I be dissapointed? Are there any options for replacing the bridge p-90 with a traditional humbucker if desired...without altering the guitar body? Thanks for any input on this topic!