Carl,
Nearly all of my imaging is through the VC200L at prime and the SXW manages this well. I have had some issues getting my guiding accurate enough at the longest focal length (1800mm) however this is normal and I have found solutions to the issues I have encountered.
In my case my early attempts at autoguided long exposures were frustrating, I discovered I have to pay carefull attention to balance (need to be heavy in the E), DEC settings (guide in one sense only) and polar alignment. Having done all that I found my issue was mostly down to software centroiding accuracy - a nasty surprise and not one you think of first as the cause of tracking errors.
I have threads eleswhere on this if you want to take look...my most recent image is this one:
http://www.iceinspace.com.au/forum/a...3&d=1181826917