Im not generally a fan of HDR, preferring to manually blend, but I don't really see why you need exif data to do HDR, just select 3 frames from the same composition.I would like to see a full resolution copy of their HDR image mentioned in the article. The one on the page doesn't show much detail.
I have tried that, this image was from a single RAW to produce 2 images then blended manually in PS. Probably could have been done just in LR but I prefer to blendHaving EXIF data would make it easier for the software to automatically pick tonal ranges from the individual images.
I have had really good results doing HDR from a single RAW image.You don't get the same extreme range that you can get from multiple images, but you can get very natural-looking HDR images. I haven't tried it with a CGO3+ DNG yet because I'm still waiting for my Typhoon, so I don't know if those RAW images have the required dynamic range.
Well it would be a long post, but in short:Dare I ask what the technique of merging 2 images is?
Have you ever tried Capture One?