I can speak to this a bit. Compared to larger diaphragm mikes from DPA, Sennheiser and the like, the small DPAs are “noisy”. And if you’re in wilderness and catch that rare moment when no airplane is passing by and the acoustics of the space are sparse, and you crank the gain to 9, then you’ll hear noise. But then again, you’ll hear some with other mikes as well.
For me it’s a non-issue for a few reasons. One, I never want to hear such spaces played back at a volume high enough that the noise of the mikes is noticeably annoying. If the space is quiet, then I’m happy to let its recording reflect that. Two, the noise is nice. Really, the few times that I’ve noticed it, I’ve found it to add a sonic character to the recording that is often pleasant. And lastly, three: what the DPAs achieve technically in their near-perfect omni presentation is worth pretty much any drawback in my opinion. I run them A-B and am regularly amazed at their presentation. Assuming you like what omnis do, they achieve it all: solid stereo information along with height and depth.