I just want to point out that cardioid mics are directional. If your band is set up in a circle in the rehearsal room, the cards are going to pick up much less of the sound behind them.
Omnis pick up in all directions. They work more like your ears.
The Zoom has a lot of internal mics but its basic X/Y stereo recording is cardioid (directional). I guess its two-channel surround sound is something like omni.
http://www.bhphotovideo.com/indepth/audio/hands-reviews/new-zoom-h2n-rewrites-book-portable-recording
It does have other possibilities but I doubt you would be using them. M/S and four-channel are aimed at film and broadcast location recording, getting files that can be tweaked in post-processing. I trust you do not want to be mixing down four channels after you record.
Anyway, cards and omnis both have their uses. If you are going to get a recorder and stick with internal mics, make sure that the pickup pattern is best for your setup.
And yes, do look at that Tascam Dr2D. Its internal mics are cardioids, FYI. Its big selling point as a rehearsal recorder is that it makes two recordings at once--one 20dB quieter, so if you do overload at your usual levels, there's another undistorted copy as well.
The PCM-M10 and other recorders generally handle overloads with limiters, which (if you enable them) will kick in when things get too loud.
I suppose the reason I was leaning towards cards, and the H2n in particular, was because of
flexibility. You're right, in the case where the musicians are scattered in some sort of circle around the room, omnis would work best. However, some sort of semicircle is much more common, or anything in between. Also, I plan on recording myself, solo. It seems to me that, taking into account all possible playing situations, then on average cards would be better suited. But maybe I have a faulty impression of how flexible the H2n is? Like I've said, I'm not too familiar with recording, but is it wrong to think that the M/S option would come in handy in my case? Or is it really only for those purposes you mentioned?
The M10 definitely looks good, but it might be just barely out of my price range. As for the DR2D, I did some minimal research and found that battery life seems to be an issue. And researching the H2n a little more, people echoed your previous point about its poor build quality. But if I had to choose between poor battery life and poor build quality, I'd choose poor build quality, if only because I completely overestimate my caretaking abilities. But hey, what can you do?
After some more thought, I really can't justify spending more than $200. And anyway, if I did, I'd go for the M10, so this basically rules out the Olympus recorders and the DR100. So that leaves the H2n and all the other Tascams (and maybe the Roland R-05? still need to look into that one...). I guess my question would be, for the cheaper Tascams (05, 08, and to a lesser extent 07 and DR2D), is there a notable difference in sound quality in the internal mics when compared to DR40, H2n, R-05, etc.? I've listened to a few AB tests (such as
http://www.wingfieldaudio.com/portable-recorder-sound-samples.html) and it seemed, for example, that the M10 is more dynamic than the Zooms and Tascams, but AB tests don't really represent real life situations, do they? I know I'm just blabbering by now, but I guess what I'm trying to ask is whether or not I should be concerned with such small differences that can only be appreciated in an AB test, when I'm certainly not trying to produce professional quality recordings. I merely want quasi-professional quality recordings to, say, upload to my website, use as demos, and (even more merely) to listen to after rehearsals for critiquing purposes. The quality of the mics is important to me only with regard to their ability to capture all instruments as equally as possible, no matter the setup, and their tolerance of high volumes. Hence my hesitancy to buy a recorder with omnis, and hence my attraction to the H2n, whose official website wowed (tricked?) me with claims of the recorder's high level of adaptability.
Thoughts?