OK, sorry, my fault, I only updated duplicity :-/
I've now updated duply to Debian'S testing version, lets see if that helps.
I've read the link you gave so when running a full backup, I basically have to first run a pre then the full then post? But how do I time that correctly as I have no idea how long each of these commands takes? That was the beauty of using backup, it would simply run them all one after another as they finish...
Preparing to replace duply 1.5.5.5-1 (using .../archives/duply_1.8.0-1_all.deb) ...
Unpacking replacement duply ...
Processing triggers for man-db ...
Setting up duply (1.8.0-1) ...