Set up they work fine. Especially they are better than the standard cutters for hardwood shafts, hickory, ash, laminated, etc. The little plastic ones don't cut the hard stuff well, but it will. The hardest part is setting up the angle of the cut. I took a cheap plastic one made a taper on a wood shaft and then put it in the tru-center and copied it. My preference would be for them to machine in a slot for the blade with the correct angle. But that said, they can and do work.
Aaron