My product keys have come from MSDN.

Your not using the Partner license, your likely on Bizspark or a bog standard MSDN subscription. Partners pay the most, then get treated like an ahole.

If buying MSDN works out to be cheaper than the Partner program, why not buy MSDN licenses instead?

MS Partner licensing gives you broader usage, through to production servers, Office etc. Pretty sure MSDN is dev or training only. Plus why pay twice, shit should just work without all the BS.