Sergiy,
Thank you for your help. I wasn't clear on what you meant by "read a response" so upon looking at the example, I saw and added the line:
Apperyio.response.success(XHRResponse.body, "application/json");
This alone did not work. I had to add a "body" option in my initial request. After adding "body" : {"":""} to my request, it worked, even after removing the response.
So for my issue with my APIExpress "PUT" services, a "body" seemed to be the solution.
-Andrew