It has of course been nice to be able to use Acrobat Pro and its preflight tools to ensure that everything is "really" ok, and I still do this as a kind of compulsory act when delivering anything to the printer, but much more simpler verifier and troubleshooter should suffice to notify problems in the output. I would gladly pay something for this kind of a tool, but not more than e.g. for a font manager. Nothing to be rent.