openSUSE has backported the new kio_sftp implementation based on libssh to their KDE 4.3 packages. This increased the users and helped to find some bugs in kio_sftp and KDE. The current implementation is working fairly well. As soon as libssh 0.4 will be released (hopefully soon) I will add more features. Users asked for ~/.ssh/config support and I've added openssh's statvfs extension to libssh. This means I can check if there is enough space on the server before I copy a file.
I've commited my kio_sftp rewrite to KDE trunk today. The patch for KDE 4.3 if you want to test it is available here. You need libssh 0.3.2 to get it working but I suggest to use the libssh v0-3 git branch which has fixes found by kio_sftp testers. Thanks to all of them!