ghost or synergy are silent based on how you plumb them. You can get a dead silent old school durso too. You just can't pump 2000 gph though a 1" pipe.
so silent has to do with how you plumb and gph you are trying to run through it not what is the best type of overflow design.
so silent has to do with how you plumb and gph you are trying to run through it not what is the best type of overflow design.