Just figured I capture another little tidbit about an environment that I was creating. I wanted to add a column to a central content type that would connect to an external data source using the Business Connectivity Services (BCS). Right now with SP 2010, I cannot achieve this because a BCS column can only be defined at the list level and not at the Site Collection level. So I cannot centrally create the column definition.
This had a cascading effect because I wanted to define this column on a Document Set Content Type I created. There is no problem with adding the external data column to my Document Set definition at the list level. However I have set up rules on my Document Set definition at the site collection level to synchronize the data to all content types within the Document Set. So I will not be able to get that to work unless I define that rule on the Document Set definition at the list level.