That's actually what we're doing right now.

Resource B doesn't always require an update though, and we'd like to be able to pass back to the client some better information on whether or not that needs to happen. Unfortunately, I haven't had a brilliant epiphany yet how to do that without adding some virtual attributes or something similar to the JSON representation of Resource A that gets passed back.

Thanks for the kind words on our choice of a bunch of technologies - it's most appreciated. :)