Since writing the original post, I've done a couple of things, resulting in a couple of observations.
1. I bought a DSLR again, a Pentax KP, which has a good optical VF, known for its clarity due to having a true glass pentaprism. I forgot just how dependent the view is on the lens... through which you're viewing the scene. That's obvious, of course, but SLR finders have a curious sort of hybrid viewing style relative to other kinds of viewfinders. Through the lens - optical is a viewfinder type that shows you exactly what your lens is going to do to the resulting image in theory, whereas an EVF shows you what the lens is actually doing. With an SLR finder, you still have to imagine how the lens characteristics (which you can see) are going to look in the finished image. An EVF shows you how that will look, no imagination required.
Incidentally, I forgot how much DSLRs encourage chimping. As in, I raise the camera to my eye, focus, and while I'm pressing the shutter I am imagining just how the image will look, informed by whatever amount of added information the camera is (cryptically) telling me through the VF, such as an exposure meter based off whatever metering mode I've chosen. It's really hard then not to look at the screen to see how close I was to what actually happened - certainly that's what image review is for. So I guess most of the time I'm not really chimping, I'm just glancing down quickly, mainly to measure exposure (I trust the camera with pretty much everything else). However, the glance at image review does briefly take me out of the scene. I've kind of gotten used to turning image review off using my LCD-only GR, the GX9 with EVF, or (of course) film cameras with no "review."
2. I saw a good deal on the smaller GR viewfinder, the GV-2 which Matt mentioned earlier, and I couldn't help trying it. Initially I felt I could live with it, now I'm not so sure. Nearly every time I go to take a photo with the GR held up to my eye, I end up pulling it away again and using the LCD. It might be a failed experiment. It's too close to the tiny viewfinders on old film compacts I mentioned in my first post - even though it's optical and uncluttered, it's just so small that the scene doesn't feel like real life anymore and the subtleties are too easy to miss.