this summer we ran in a river landscape some dpa and dynamic md 441 with small recorders. we had 2 mr1 korg, 2 Microtrack (the better preamp is the older one) and 1 sony m10. for the dpas (4063) we needed pip 3v or 5v (microtrack has). The Korg MR1 ran shortly till battery was exhausted, needed reloading with a field solution. But it sounded best of all, nearer to professional gear, preamps clearly hissed a bit, but without problem near a hissy running river. MT 24/96 was quite good sounding too, but a bit too crisp (like good amateur gear). both MTs sat out from humide air. the contacts of the cf-cards caused it.
The M10 is a reliable, easy too handle machine, especially with the dpa (4063) and dyns, no batt problems (2 AA ran a week) and so on, but in my ears it sounds not as best. like the older MT24/96 (not bad like many people claimed) it has nearly no hiss. On dynamics we needed specially soldered symmetric/asymmetric (it's a bad direction) cables or caught a really insufficient sound profile. after all: the sound of M10 seemed us to be a step restricted; colorated differences between pro and user gear?
our landscape experience let us feel the lack of a pro sounding small recorder. some middle dimensioned recorders (Marantz, Fostex, Sony) soundwise are nearer, meno coloured, but loosing the advantage of smallness, but only nearer, not quite target reaching.
We had no pdm 620, but some weaks ago i heard 620s tracks, for my ear it's half stepping to pro sound, but still coloured; so Korgs old Mr1 preamps are sounding better, more neutral with a kind of good saturation but a little hiss, but the need of external power solution not only annihilates the smallness, it causes unstable connections. so where ever possible we turned back to heavier pro sound gear. Yes: the Korg with two symm intros was not a bad start. But whereto runs it nowadays.
let's try to discuss the question of sound. in real work it's most important, but not easy to debate. noise and sound quality are different shoes.