My experience with Lo settings is that they are very close to the same as the base ISO in terms of image quality. I use them fairly often, in fact. They are useful for getting a little less sensitivity when that's an issue, such as with ND filters, looking for less DOF, needing slower shutter speeds for panning, etc. Tests have shown that there's somewhat less dynamic range than base ISO, but only by a small margin.
It's true that they're not native; they require amplification to reach these ISOs. In particular, they use negative amplification, which tends to compress dynamic range.
I've posted a fair number of files from Lo ISO settings over the years, and there hasn't been a single comment on them yet. I doubt that many folks have even noticed.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!