Some would say that if the update corrupts the system files then your suggestion will not work: http://www.eightforums.com/performance-maintenance/44172-dism-restorehealth-failes-error-0x800f081f.html
If the log messages that are shown there were the only significant ones then the "corruption" involved very old modules. (This is something that has perplexed me with IE updates too. Why are they failing try to find such old modules? And I have speculated
that perhaps injudicious "cleanup" may be responsible?) In any case, I think they would not be using the source correctly to repair corruption if they were trying to point it to an updated image (especially if they had used /resetbase to get there. <eg>)
I think it would make more sense to point to an older image, which some users might have.
and also here: http://answers.microsoft.com/en-us/windows/forum/windows8_1-windows_update/error-0x80070005-when-installing-kb-2919355/a7fddff5-4ab9-4077-baf1-3fb030e73877#LastReply
There are also a number of posts on this and other forums which indicate that a repair-install is the only solution to the corrupt files issue and simply pointing /restorehealth to a good source whether sxs or a mounted image will not work.
Unfortunately most of us do not have media available in order to test this proposition, but those who do indicate it requires a repair-install rather than a known good source. There has not been a peep out of Microsoft about the issue, but what else is new?
It does make for interesting discussions and suppositions for those who enjoy such discussions, but until Microsoft deals with the issue it will remain an interesting discussion and supposition for those who are into such things but not a practical resolution
for most users.
Until I have actually tested my ideas I would of course have to defer to others' experience. I was just pointing out what the DISM documentation seemed to imply. So, if it doesn't work the way it is described, what's wrong: the document? my interpretation
of what is written? or the program being documented? <eg>