I would have gotten the PCM-100 but it would not be practical in my situation. I'll be backpacking in equipment and recording as an ancillary activity. I will be buying two setups which I will locate separately and double my chance of getting some night-time, wildlife audio. Take the PCM-100 then add mics, and anything else needed, and then double it. I'm brand new to this and know squat about recording equipment. It would simply not be prudent to be dropping that kind of money into something I know nothing about nor have any experience by which to guide my decisions.
I'll start with the M10 and relatively inexpensive microphones. If I enjoy the results I'm getting, and want to improve them, then Hell's bells...I'll buy better equipment.