I have a non-audio remote 25 and haven't tried the audio one, but anything that's been said regarding the OS quirks, shoddiness of the manual, lack of editor, etc. etc. would apply to both versions.
What you wanna do sounds like it should work, the only potential stumbling block i can think of would be latency issues with the remote 25 when it's trying to generate midi, whilst inputing AND outputing audio, over a feeble USB 1.1 cable. You could well find that yourself needing to reduce the sampling rate or number of channels for the sake of audio stability and responsiveness of the interface. It would certainly be a very tidy integrated solution for live if it works well. Maybe put some specific questions to novation about what you want it to be able to do and see if they can help.