I think we have an invention looking for a use - or am I being unimaginative?
One could feed a soundboard or mixer to the H4n's line-in and record what's actually being heard by the audience with its internal microphones. Then mix in post. I don't know...just one possible use, I guess.
What I hope to do for my classical/acoustic applications, assuming its internal microphones are usable (yes, I realize this is quite an assumption), is just record the hall with the internal microphones (facing the audience) and connect a stereo pair of SDCs to its microphone inputs as the main pair. Just because I don't have the money for a proper 4-channel recorder. Not sure if this is a bad idea.