My mistake, it seems that I misinterpreted your goal. I assumed you were going for physical accuracy and based most of what I said off of microfacet models. The statement about Oren-Nayar having more in common with Phong specular was limited to "The result changes as both light direction and view direction change."
Anyhow, glad to hear you have a solution you're happy with in Minnaert (which sounds a lot like what you propose with inverse N dot V)
Yeah, thanks. It does seem like Minnaert (at least as interpreted by Blender; I've heard rumors that "Minnaert" refers some different but related functions, some of which seem to be more physically-based than others) is what I am going for; I read the glsl code for Minnaert and Oren-Nayar, and (as everyone said), there's no way to get the light angle to go away in Oren-Nayar, but to my great happiness, Minnaert doesn't rely on the light angle at all (except as dotted with the surface normal).
Have some up-votes, everyone, but know that this doesn't mean I won't probably come back tomorrow with even more stupid questions.
I'm going to post some screenshots from Blender in case they might help explain what I'm going for. Here is an image with the Lambert, Minnaert, and Oren-Nayar GLSL materials; when the viewing angle is similar to the light angle, Minnaert and Oren-Nayar look very similar (and could potentially be tweaked to be more similar):
And here's the same three (I flipped the image so that Lambert is still on the left) with a viewing angle that's very different from the light angle. In this case, Minnaert is the odd one out, which, knowing what I know now, makes perfect sense:
In any case, the Minnaert shader gets the "rough" look I was hoping for, and I don't know enough about either the origins of this Minnaert shading or physics to say how "weird and unphysical" this is (I've heard that it's based on observations of the moon, but I've also heard that about Oren-Nayar; the fact that almost everyone who's replied so far thinks intuitively that what I'm after breaks some kind of important rule of physically-based shading suggests that maybe Blender's implementation of Minnaert is strange or even "wrong")
I'll probably post an update concerning whether I find that using this kind of function (but obviously not Blender's GPL'd code...) in my own game makes it look prettier -- if nothing else, it seems like something that hasn't really been tried much, so I'm curious.