After taking HDMI captures using a StarTech PEXHDCAP it appears that the "FCEUX" palette on the Hi-Def NES isn't acutally the FCEUX after all! I used Loopy's PALTEST NES program (http://nesdev.com/paltest.zip) that uses HW tricks to display all of the NES colors on screen at once to capture the 7 palette choices available on the AVS and Hi-Def NES (4+3 respectively).
Here is the FCEUX palette comparison (AVS then Hi-Def NES). Notice how a number of colors are quite a bit different, especially in the red colors.
|AVS FCEUX aka "Improved" Palette
|Hi-Def NES "FCEUX's" Palette
Notice the darker reds along with de-saturated colors that do not match the original palette