How to analyze HDRI images for CG Lighting

Recently was told that an HDRI I made had no dynammic range built into it, which is strange because I combined 6 photos with a pretty wide range of exposure. I believe that they may be correct because the light interaction in the CG renderings is very weak.

I combined the photos using Photoshop's Automate>Merge to HDR Pro feature. Does one need to manually convert the HDR to 32-bit color after creating these?

What is a good appproach to analyze the HDR once it has been created? The histogram isn't working in 32-bit mode.

Are there any other methods of analyzing a HDRI to determine that the range is wide? I applied an exposure adjustment layer, and it looks like its working correct, but I can't be sure if that's helpful.