After looking at your concat.qvw I was wondering why you made the LinkAB table. That is just a resident of the concat table which already has all data in it.
And you wrote that the dimensions do not behave in the concat .qvw. But i think that they don't behave right in the link table. For example:
When selecting XXX in the DimLinkOne both value A and value B are associated. Next i add the selection GGG in Dim Two. GGG isn't connect to value B at all. But in the link table it shows 300 as a sum of value B and in my opion that isn't correct.
Of course i don't know the business rules behind the data model. Maybe you can explain it a bit more for me?