The healing and damage numbers over the portrait portrait in the default player frame won't appear after using this.  The frame that contains that information is the PlayerHitIndicator frame.  Unregistering a simple combat event from the player frame does the trick without any other apparent issues.  All other things on that frame come from other events.

To make them appear again just disable the addon and reload.  While this addon is in Beta be prepared to do this if anything occurs unexpectedly.

Some forums and addon authors use PlayerHitIndicator.show = function() to do this same thing.  I believe this to be a far superior method than that.