The non-cool BI tools work alright with multiple sources and integrating them into a common OLAP model that takes care of automating the relevant backend querie

The non-cool BI tools work alright with multiple sources and integrating them into a common OLAP model that takes care of automating the relevant backend queries. This is a valid approach if you do not want to move all your data into a DW before reporting on consolidated views, but the there is no magic bullet in terms of which model is optimal. I am talking about Oracle BI, SAP BO, Cognos BI.