I have been using Roon for sometime and have enough experience with jRiver to understand its issues, in particular with its busy interface.
Roon does not support DLNA, which would be the protocol required to send audio files over ethernet to PS Audio Bridge. Roon's engineers state that DLNA does not allow the endpoint to control its own clock, something they claim will make it less than ideal for streaming audio to your DAC. They just released their own protocol and have a number of manufactures supporting it. Their protocol is RAAT and its more friendly name for it, Roon Speakers.
The SDK was recently released and Paul McGowan has noted they are looking to support it on the Bridge II, but need to determine if they will have the space needed. If not, I would expect future products to include support and it could be possible that backward compatible products may be produced if demanded.
Roon has an iPad application and it works very well, but either an Air or Pro size is recommended as the interface is highly graphical. Its identical to its desktop interface, which was designed with touch panels from beginning. They are likely working towards an app for the iPhone, but the interface would require a redesign and they put an effort to provide a clean and clear UI. At the moment its a matter of resources and RoonSpeakers is getting most of the attention now.
Roon is vastly different than any music library management app you have ever seen. The key behind it is metadata and the breadth of knowledge it brings to your library. Compared to jRiver, it will seem highly inflexible, but I personally enjoy its simplicity as I deal with complex system daily and could use with one less.
If you have any questions, please let me know and I answer the best I can.