I was using WinSCP for some time and I think it is a very good work done by Martin. However I needed a full-featured drive functionality and "Keep remote directory up-to-date" suffers from some time-synchronization issues, so I'm now using a samba bridged through ssh tunnel. A good guide how to configure that is for example here.
This led me to idea, how to manage an often requested feature of mounting SCP directory as a remote drive. I think that it shouldn't be very difficult to "learn" WinSCP to listen on localhost for samba connections and brigde requests to/from SCP directory.