I finally figured out why lighting in this game bothers me so much, and here I was thinking it was just the HDR to blame.
After messing around a bit with the tonemapper I decided to do a straight gamma 2.2 conversion (I'm like 95% sure this game is doing everything in linear, like most games, but I look forward to finding some place where its not....) Anyways a straight gamma 1>2.2 produces an image that is crazy bright. It turns out the stock game isn't converting things to a proper output gamma, which is obvious if you know where to look;
Now some might say the above is fine, or even great looking, but its a sign that things aren't being converted to the proper gamma. Cylinders like that actually have a fairly strong terminator line, like so
Adjusting the lighting so gamma can be converted to 2.2 and still produce a respectable exposure gets things right;
Doing correct gamma adjustment also fixes some of the more annoying issues that pop up elsewhere, like the radioactive grass soviet russia seemed to be covered with - and before they even had a nuclear accident!
Or the strong soviet wood that glows all on its own
Doing this also ends up with frame buffer that covers most of the histogram, meaning that a nice toe and should can be added without crushing the shadows like the stock HDR does.
It also results in a much more reasonable tonal range overall. Thins look more like they should and less, how should I put this, oblivionesque
Even the trees look better
On the downside, there are a few emissive textures that have to be changed now, but thats no biggie. I can finally get a nice full histogram to grade instead of dealing with half the image not being there.