Hell, I don't know.
If you want a fast cutting chain, why use a semi chisel.
Those are mainly run by arborists and other amateurs here.
Also, I tend to look down on people who can only sharpen using some kind of device.
If one does chainsaw work for a living, one should learn to sharpen with just a file, no crutches IMO.
I liked the idea of filing with the saw upside down, never seen that before.