PEC for the Sphinx mount should be available towards the end of April. This will greatly assist in the quantity of guiding corrections. Last I heard, it will be released as a firmware update. If the mount is ASCOM compatible, I recommend you use
PEMPro to program your PEC, not just autoguider adjustments. PEMPro will significantly reduce your PE.
IMO, 3.4 arcsecs per pixel is a little high, especially when considering the focal length of the main scope (.74 arcsecs per pixel). Increase the focal length of your guidescope or reduce your pixel size.
There should be no issue with the Sphinx handling the focal length of the VC200L, though you should try to match your cameras pixel size for deep sky objects. Dennis explains this extremely well in the post -
http://www.iceinspace.com.au/forum/s...ad.php?t=15250