I purchased this sander to sand my decks and it worked great!!  I wanted a work horse tool and I think I have one.  With about 12 hours on the motor I cannot pick up on any abnormal sounds.  I may be too critical here but I am giving the sander 4 stars because of the dust collection system.  I think one reason why the bag does not collect as much dust as it could is because the bag's wire attachment fixture does not seal the bag around the port so dust blows out of a small hole.  With that in mind, wearing a well-fitting dust mask is a must for the operator and those who may in the immediate area.  And yes, it is noisy so I strongly advise wearing hearing protection.