Power line conditioners- to use or not to use? That is the question?

If you are in the "yes use them" camp.  Which ones etc.?

If you are a "no". Why?

Right now, I use outlets I built from hospital grade outlets bought from an electrical supply house.  I plug my amp directly into house wall outlet.  In speaking with a friend he highly recommended using a power line conditioner.  Specifically a panamax mr4300.  Swears by it.  Thoughts?