New
#11
Depends on whether it has the same hardware configuration as the one you are working on. If it has different hardware, using it to make an image to restore the one you are working on can cause its own issues in trying to load drivers that are for components that do not exist in the one being restored.
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I took a few minutes to look up the Surface RT. Looks like it only came with one configuration, save the storage which came in 32GB and 64GB variants. An image made with another surface should work without an issue. However, it looks like you are already working off another surface image so I dont know what good buying another one to make an image of it would do for you.