this is a known bug since backinthedaze. apple seeme to have given up. i think it worked properly in OS X 10.1 but then stopped working. the error is that the transfer doesnt stall, but simply seems to have stalled. if you use menumeters or a similar monitoring tool, you can see that the mac still upploads, even though the connection seems frozen.
use the latest version of transmit to access webdav folders properly, this is the best cure. with the latest transmit version, you can also create a droplet that contains the password for the actual webdav directory. this is handy to have in the dock or finder sidebar!
webdav is neat for sharing files with novice windows users w/o FTP clients installed. just mount a web folder and go. all built in to XP. remember to swittch off .DS on remote servers in for example tinker tool. then you wont upset anyone non-mac.