Hmmmmm. I tend to judge it based on "If this problem arose with one of our clients, who would be tasked with fixing it". Chances are, if it's something I would find myself needing to fix, I let it be.
However, I'm also a hardarse and have better things to do with my time than figure out how to colour code contact cards, so I would likely tell the user that I can't help them with that particular problem and they will need to just work with the system.
However, if the situation was "It works on standalone Outlook, but as soon as I connect it to our exchange server, it works differently" (such as flags in Outlook 2010 when connected to an Outlook 2003 server), then that's 100% applicable for here.