I don't get a clear impression that it's worthwhile to record 24-bit with this recorder, even though it supports the format.
I'm unaware of any tests on any small recorder which make a persuasive case for using 24 bits to demonstrably reduce noise under real-world conditions. For me, 24 bits is a safety net if you set the record level too low by accident, or if you want to be quite sure you don't get digital overloads on unexpected peaks and for that reason record low.
Meanwhile, I've been using a pair of Roland binaural in-ears with my M10 - whose internal mics I am famous for hating, but I don't always want to be walking round clutching an external mic - the stereo imaging on speakers, as well as on headphones, compared to the internals, is staggeringly better.
I do think that the impression given by many users of the technique that binaural sound isn't good on speakers is incorrect. Maybe on headphones you get the best results, but speaker replay is still impressive. Listen to
http://www.youtube.com/watch?v=RVf2sku8_W0 from about the 4 minute point. For me, on speakers, that plane goes by overhead, and is not on the same vertical plane as the waves. (Note however that I tend to listen to speakers a bit too close so they are at a wider than normal angle to my head).
Anyway, my M10 is now likely to get some renewed use. I'm hoping to get an opportunity to record a bit of live music with the binaurals before long. Meanwhile I'm having fun recording trains and supermarkets. With the former, I've made a point of recording a test not with the train doing the usual thing of passing from one side to another (yawn), but I stood facing along the line of the track so it came from behind and disappeared in front. Left/right any reasonable stereo mic can do, front / back requires binaural.
The biggest problem with using in-ear binaural mics is forcing yourself to keep your head pointing in a consistent direction, so that the stereo image doesn't whirl around on replay. A surprisingly un-natural thing to do (especially when watching tennis from the side!).
