Oh, you've seen this. Sorry, I didn't make a proper issue to track.
I'm on Debian Linux uktnlx01 2.6.32-5-686 #1 SMP Sun Sep 23 09:49:36 UTC 2012 i686
I've seen other people with this error (not with SshNet but other hacking around) and they solved it by taking out the path sent along with the D0755. The fix was indicative, so if you have a more robust idea then go for it, although I have no idea how to determine the path separator for a remote SSH system, I just assume a Linux style /
Cheers Oleg.