Hi there.
I have no idea what the DR-100MKIII internal mics sound like but, I recently purchased a slightly used AT2022 from a friend on here and am happy with results from the few times I've used it.
Two of the three times I used it as part of a matrix with a soundboard, and I did use it standalone/wide open at a recent outdoor blues festival and they sound pretty good.
The mic can be set at an either 90 or 120 degree pattern, I've only used them in the 90 degree pattern.
That's about all I can mention, for now, hope it helps.