I use regularly the internal guider of Kstars. Usually I guide at +/- 0.5 arcsec with f=510mmm and 80mm diameter, on à finder 9x50 and a QHY224C. I prefer having one software than two. The internal guider borrows a lot to PHD2. It's a good thing to active the GPG option also.
You must do the calibration on the equator and near the meridian