I personally have never used a power conditioner and never even thought about getting one until I have had a rack for one to go into. Personally, I have only heard one comment "you'll be sorry, when all your kit blows up". I have always thought that was the point of a fuse, it pops before your gears pops. Is it just me or does a power conditioner serve no function beyond the fuse in your kettle lead? Which it is plugged in via.
On the smoothing side I presume the Kemper has an internal power smoothing circuit, correct me if I'm wrong.
That may have come across a bit harsh/arrogant but, is there any reason for getting a power conditioner?