If you’re getting the above error immediately after clicking mount it seems to be because you are using OSX 10.6. There’s not a ton of good documentation but this is what seems to work.
Right click on the app and select “Show package contents”. Navigate to Contents/PlugIns/sshfs.mfplugin/Contents/Resources/sshnodelay.so and delete or rename the file.
It should now magically work.