I've just installed Cyberduck to try it as a SFTP client to access n900 and - my God - i think i never gonna use anything else. It gives maximum speed possible over WiFi (but you need to specify in Settings that you want transfers over SCP, not SFTP), connects in seconds, gives you autoloaded bookmarks and maintains previously opened directory view. This is so great that i don't want to return to old methods of transferring files between big computers and the tablet, like WizardMounter and samba shares.
BTW, i didn't try WinSCP on Windows, and it's being praised by everyone.