Earlier quoted context omitted.
In Office Professional Plus, PowerPivot. IIRC, LO/OOo have much poorer support for tables and table formulae than Excel, as well.
What percentage of the user base uses that functionality? Especially considering that at the point you require the ability to "import millions of rows of data from multiple data sources into a single Excel workbook" you should probably be using a proper database and stop playing around.
Tables or PowerPivot? I'd say a substantial share of the institutions purchasing Office Professional Plus are using at least one of the two in important processes, even if only a small number of users are directly aware of it.
> Especially considering that at the point you require the ability to "import millions of rows of data from multiple data sources into a single Excel workbook" you should probably be using a proper database and stop playing around.
PowerPivot is (built on, at least, the feature includes more than just the database) a proper column-oriented OLAP database.