Just to be crystal clear, I see what you're saying now regarding the toning (although I don't seem to have those presets for some reason). You'll get the same popup if you go to Image -> Mode and try to change it from 32 bit to either 16 or 8.
I actually don't like this popup much personally. All of the options it gives completely change the image which isn't what we're wanting to do exactly. Here's an example of my process below.
Here's an image of my Dosch HDRI...you'll notice it's washed out, the sure sign of a gamma screw up.
Interestingly this package I bought has about 8 different files with the same general image (a couple different mappings like cubic and spherical as well as a few different resolutions). Interestingly, the 12k resolution version had the correct 1.0 gamma so i have this as a reference of what I'm trying to get.
Going back to the original (washed out) image I apply my gamma adjustment, which I found out from wikipedia is .4545 (or 1/2.2) if we want to be anal. As you see it matches up pretty great with the 12k image I know is accurate. Now it's not washed out at all.
And if you're going to save this as a 16/8 bit image and have to use the hdr toning box, there's only one setting that will get you through without altering the image. I tried using this box instead of the gamma adjustment I show above the the image comes out completely differently, so I wouldn't recommend it.
-Brodie