The resolution seems to be .001 although if you are not holding your breath or keeping it against a surface it will dance all over the place. Just dragging it across a surface and it will bounce a little. As far as accuracy, its seems to be within about .008" which is better than its spec of .015" for surfaces that I consider to be flat. Unfortunately, I have no precision anything to check its accuracy beyond like the surface of my table saw or a metal striaght edge designed for workworking. For me, ignorance to the contrary is bliss and the unit seems quite precise. For nearly $2k, it'd better be.
Someone posted a link to a site that had a multitude of encoders that were 2000cpr with quadrature, and at only $50 each that seemed cheap. With a 12" arm, that would put the resolution at about .018" which might be good enough.
Cliff