I can confirm that both versions of the WAB and Identify widget are the same (2.1).
This is an obvious oversight on my part but because I could not add Image Services to the Identify widget I tried using their matching Map Service url when configuring the Identify widget. Clearly the layers must be in the map to use them, rather than just be accessible through the REST endpoint. I changed the underlying Map to one with the map services and the Identify widget works. I apologize for not thinking of that sooner.
So, I guess my issue now is whether the Identify widget works with Image Services, which according to the REST Services Directory shows that they do support Identify. I am unable to add the url (copied directly from the browser address bar) of an Image Service to the Identify widget configuration.
Thank you.
Matt Levey
SeaSpatial Consulting