Hi Experts,
unfortunately, I just realized that for CRM 7.0 it is not recommended by SAP in general to enhance the BI content for Online Reporting. As from EhP1 there seems to be an Interactive Reporting Enhancement Workbench to support this requirement. See post from Sven Kriebel:
CRM 7.0 - Enhancement of Data Sources for interactive Reporting
So until the next upgrade I will have to stick with what AET provides.
Anyway, thanks a lot for your helpful answers!
Cheers,
Jens