Personally I have not used one.
There have been some members here in the past that have had them, and there was a company that produced them to fit a CC. I only personally know of one member who has one, but last I knew he never mounted or used it. Most were floating, but may have had a lock to where down pressure could be provided.
Disadvantage to down pressure is obvious... you will lose traction, so extra weight is necessary. Disadvantage to center mount is that the machine is so short, it will be hard to make anything level.
Advantage is....
I don't know if there is any. It looks cool?
