Quoting Per Bjornsson <perbj@...604...>:
The PDF backend of Cairo can be expected to improve (currently it shows promise but doesn't really work for any advanced stuff as far as I can tell - it does already do transparency though, at least for flat colors!) and should probably be the preferred hardcopy output method.
Cairo's PDF/PS backends will be most appropriate for printing, but I don't think Cairo-generated Postscript or PDF would always be desirable for our "export" functionality.
The reason is that Cairo writes PDF/Postscript shapes tesselated into trapezoids, rather than as paths with fills and strokes (at least this is planned; I don't know whether that is the reality yet). This is highly desirable for printing because it ensures consistent rendering regardless of the renderer used by the Postscript interpreter (there are corner cases that most commercially available Postscript implementations don't get right).
However, many designers also rely on EPS/PDF output as a "poor man's" interchange format as well. We at least want to provide an option for Postscript/PDF output that preserves as much of the structure of the document as possible, to enable meaningful import in other tools.
It'd be nice to separate the two roles somehow, since in the more common cases where editing isn't needed (e.g. for just sticking in a page layout), the Cairo exported EPS/PDF is probably going to be preferable.
-mental