Frank S, Hi,there are a few well known flail type mulchers on the market,(Mighty Mac for one),that are legendery for longevity.Blades off the shelf items and I've worked on many commercial units that are ganged behind tractors that use the same system the bigest advantage over a fixed blade is that they fold away if they encounter a hard imovable object,(doesn't mean they don't get damaged), this tends to remove shock from the drivetrain which is a big plus when it is gear drive. Most are double sided or like a fixed blade but with a bearing in the center. It is a good system and well proven.