A little bit late - with SP1 the problem no longer exists - we finally received information about how to successfully slipstream an SP2013 installation with March 2013 PU and a later CU.
As March 2013 PU was a prereq for later CUs it was not possible to slipstream it using normal methods as the files from later CUs had to replace the files from March PU - which means that the March PU packages would not be there before installing.
But there is actually a workaround which was just revealed and which has been documented by Anthony Casillas one of my colleagues in the US on his blog:
Gossner, is there any problem if my client downloads those ISO images from MSDN?I'm asking it based on Office's licensing difference like OEM, VLK and such. Does SharePoint has this kind of "different" licensing. It's a big help to deploy Sharepoint with slipstreamed version and the "public" websites doesn't have it!
Hi Maicco,for production you should download the images which contains SP1 already from VLSC or MPN. For development from MSDN.Cheers,Stefan
HI StefanThat is an interesting comment and not what I expected. That implies there is a difference between the MSDN and the VLSC editions.. What should I do if I have already installed a production system using the slipstreamed MSDN edition?