Personally, I don't see a need for the said. However, many people do.
With regard to the aftermarket guide rods . . . At one time, I swapped out my factory recoil spring/guide rod assemblies for aftermarket ones. Eventually, everything went back to the factory configuration. I didn't realize any productive benefits.
I bought 3 for all my glocks for $8.00 each. I got them from here but they don't have them listed. Give them a call. http://www.gtdist.com/Default.aspx Ask for Justin he knows the right one to get for you.