Two Paths to Making a Pseudo HDR from One Image

So, I took up my question from yesterday and gave it a try: How does the processed version of (1) a single RAW image file compare with the processed version of (2) a RAW image file that has been manually adjusted in Image Data Converter (or the editing program of your choice) to produce extra RAW files at various levels of brightness? (Here, I ran the file through IDC and produced adjustments at -2, -1, +1, and +2 to run with the original file through Photomatix 5.) In both of these tests, I used Trey Ratcliff's "Quaint Hobbit Holes" preset, and I also bumped the contrast on each image to "mild".

The image that I chose for this comparison test is another shot from my "On the Road Again" files from the other day. I snapped a picture (ok, 14) of the Long Rapids Township Hall as we were driving by.

First up is the processed version of (1) the single image file:

Next, we have the (2) version for which I took the single RAW file above and generated four other images at varying levels of brightness (as indicated above):

Differences:
The first file weighs in at 17.5 MB as a JPEG file; the second, 19.2 MB.

Visibly, the only major difference that stood out to me is a color difference that appears on the red "Danger" sign above the "NO TRUCKS SIGN".

Verdict? I'll probably keep testing to see if I can arrive at something more conclusive.