It looks like cups doesn't want to work when gs is compiled without the libcups dependency - I guess that seems obvious, but it wasn't obvious to me that the version of gs in dsl had a libcups dependency and that still worked with cups...
It would be relatively easy to separate out libcups from cups to avoid gs users having to load the large cups extension, but I wonder if it wouldn't be better to recompile a gs extension to be used specifically for command line conversions - based on my quick test, it would be smaller than the current gs extension and would not need cups.
What do you think?