Dirk,
I'm not familiar with MDG to know how DQ exceptions could be corrected back in the source.
The IS Accelerator sales guys claim it can enable corrections back into the source as identified by IS (DI), even when the DI connection is different to the sources and showed how exceptions can be exported to Excel and imported back in before scheduling the rectification.
My point? MDG may not be the only tool considered if the requirement is purely data corrections. We looked at IS Accelerator as IS does not manage the workflows to assign and prioritise once exceptions are identified through rules. See idea D28035. This should be standard IS functionality so users do not have to move around different tools to manage the DQ process.
I've also seen a demo of Agile Data Prep (being sold as IS if you want HANA) that allows corrections of data in data sets brought it, but does not appear to fix back in the source.
regards
Adrian