Love the post (will be seeing the Doctor any day now)
However I have major issues with the topic. We have multiple Exchange 2003 servers currently reporting constantly that we have hit our limit for named properties (gone way past the warning point) and we need to increase it. We haven't increased it to the hard limit as yet.
After logging support calls regarding this, no one could explain to us how they were used or what would happen if we did increase our quota to another level or even what we were losing by not producing a named property for randomjunk. Everything seems to be working fine, even though many emails are trying in vain to create named properties for things like x-header:randomjunkname.
Your article states "Should Outlook be unable to map a named property, bad things happen." But you never explain what you mean. And I can't find an example of the "bad thing" on the MS site.
Care to explain why I should care if the named properties are full?