Thanks for that link. That does seem to imply that the I2S interface can be recognized. I am just surprised that I've been unable to find info on the topic of I2S compatiblility with JRiver.
To answer your question, yes, it will work when selecting the Pi's built in sound device. The "renderer" function seems to work well also the pi's regular sound jack, but don't want to use the Pi's built in device as a audio device, because of it's limitations.
The Hifiberry audio device that I have is a "HifiBerry DAC". It is also considered an I2S device. It is an onboard DAC as opposed to a external DAC, and mounts to the PI via a daughterboard, also referred to as a "PiHat". For it's output, it uses 2 analog rca jacks mounted on the board, but of higher quality (192kbs) than the Pi's build in audio. There are a few linux audio players that work with this HiFiBerry card , (Volumio, for example) but the the JRiver's ID is the best at streaming from a DLNA as a renderer without a breakup in sound. I'm starting to think that this device is not supported.