One feature I miss from Artworks (Acorn's version of Xara DP) is the ability to have "internal" arrows instead of the external arrows we have now. The arrowheads can start at the end of a line (external) or finish at the start of the line (internal). I used that feature a lot for technical design.
I now have to fiddle with the positioning of the line end when I change the line width (because the arrowhead will get bigger and go a bit too far).