I am using ppom and it is running fine.
When I export the meta and import it on a subdomain, the radio button images do not show on the front-end of the subdomain. They are, however visible on the back-end (admin) section of the subdomain.
I see in the .json file for the export that the images referenced are hosted on the main domain. This is fine, as I do not want to have to upload new radio-button images on each subdomain.
I do have CORS set on both apache and nginx to enable cross-site HTTP requests.