This is one of those FWIW personal opinions so take it with a grain of salt.
When I first started using Windows 7 and began playing around with the 7 imaging tool (as well as Macrium and Paragon
free) I noticed that if I was using a file or folder that would normally be included as part of the imaging process, it didn't always get updated in the image. Also, there were at least a few times when I tried to use the image and it was corrupted. I simply figured it was because I was using the computer at the same time the images were supposed to be made.
For those reasons, I really, really try to schedule my images for when the computer will not be in use because I'm really, really paranoid. FWIW.