from the MDT release notice:
One of the changed items is:
Switched to using DISM for imaging processes (instead of deprecated ImageX)
Some people might think this is a good thing, but I actually think this fix is bad.
ImageX.exe is the old tool used by Windows Vista to capture and apply *.wim images. The tool was superseded by dism.exe /apply-image and /capture-image. Really it didn’t matter since they *both* used the same wimgapi.dll API calls.
Why is Dism.exe better? Well for capture scenarios, it makes the process run much faster, turns out there was a bug in imagex.exe that would cause it to stop processing for 15 minutes at the end of the capture. Well it would be better to use dism.exe for capturing.
The problem with dism.exe is that MDT doesn’t have the ability to capture the progress output from the program so it can’t display the pretty progress on the Task Sequencing Progress Bar. For Capture images, that’s not a big deal, but for image apply it would be better to keep imagex.exe, since MDT can capture the output from the program and display progress for Apply. imagex.exe apply didn’t have the imagex.exe 15 minute wait at the end so there was no need for it there.
During MDT beta I sent feedback to the MDT team that we should revert back to ImageX.exe for captures, but they declined to fix.
Please feel free to “upvote” my bug on the Microsoft Connect Site if you agree: