Hi to all!
I'm new to the game, hopefully starting with a PCM-M10 if I manage to buy one.
...
A few thoughts if you're recording nature sounds...
The EM172 capsules are a great suggestion, and they're fairly low noise (14dBA iirc). If you're handy with a soldering iron, you can buy the capsules cheaply and make up your own external mics which will power from the M10's "plug-in-power" just fine.
Interestingly though, the M10's internal mics are themselves actually EM172 omni capsules! The problem is that they're mounted too close together to give much spatial effect. One simple DIY approach to improving matters is to make some kind of baffle to put between them. There are a few references to this online if you search. I used a block of closed cell foam (about 4" square and 1" thick), with a central slit to push over the M10. This arrangement is rather fiddly to use in earnest in the field, and you then need to fashion some kind of windshield fo fit over it all, but it helps to widen the image by reducing the correlation between the mic signals, and it makes for some interesting experiments.
For recording quiet nature you really have to keep some distance between yourself and the mics, as they really will pick up every breath & rustle of clothing. Miniature tabletop tripods are useful, especially the ones with the flexible legs which can be bent around objects, as are the various types of clamp often sold for camera mounting
If you buy one of the furry windshields made specifically for the M10, you'll be stuck with the mics as they are with no baffle. I'm not sure there's much practical difference between the brands as, when fitted, you have the option of a) having them fall off or b) covering the display! The M10 isn't made for such things in the first place and there's no proper means of attachment. Even the Rycote mini-windjammer which I used was quite useless from a practical standpoint. I found the best option was the aforementioned foam baffle with an old knitted woolen hat pulled over the whole machine! The baffle also acts as a spacer to keep the fabric away from the mics. Use a dark coloured hat (or knit your own in a camo pattern) and it's ideal for leaving in the woods...
As for batteries, don't bother with the fancy lithium ones. A couple of Eneloops, or anything 2000mAh+ will power the thing for ever.
The M10 is a great little recorder to keep with you in case an interesting soundscape comes up. Just don't leave it out in the rain like i did with mine