according to Cyanogen, "In most cases, you can set Binning to 2 or 3. Binning 1 is only required when you are using a separate guide scope that is a much shorter focal length than the main scope. The guide camera can have 1/10th the resolution of the main camera and still guide very well, since the software can measure the centroid of a star to a tiny fraction of a pixel".
http://www.cyanogen.com/help/maximdl/Autoguiding.htm
FWIW, my guide system works fine with pixels that are about 1/5th the angular resolution of those in the imager.