Hey rhysjoe, Since MRU Blaster is only cleaning out a list of most recently used items from the registry....one should have no problem deleting ALL the items MRU finds. It in no way deletes actual files....it deletes a list of item names you may have typed into the Files Find box or the Start\Run box for example.
Everything is safe to delete...after all, only the most critically paranoid person who needs to relieve her constipation will resort to using it, of course I among many others.