1. YUV-V3:
This is identical to the "natural" palette you may already be used to from the default NESRGB board selections, with the exception of 4 dark green/cyan colors being corrected using Drag's palette generator algorithms. This allowed for a consistent transition from dark the light, with faithfully reproducing the more bluish tint to these colors as the original hardware displays them. Below is an example from Mega Man 2 showing the YUV-V3 version on the left versus the original "natural" palette from the NESRGB board:

2. Unsaturated-V5:
This is a more interpretive palette that attempts to reproduce the brightness/contrast levels of the original console, without over-saturated colors. It was made combining direct-capture results, manual corrections, and algorithmic corrections. Below is an example on the left compared to the "natural" NESRGB board palette on the right:

The zip package contains three optional NESRGB board firmware updates as follows:
Playchoice 10 (garish) >>>>> Unsaturated-V5 >>>>> YUV-V3
Playchoice 10 (garish) >>>>> YUV-V3 >>>>> FCUX (improved)
Playchoice 10 (garish) >>>>> Unsaturated-V5 >>>>> FCUX (improved)
Here's the download:
http://www.firebrandx.com/downloads/nes ... 0-2016.zip
And below is the project page with full details and firmware update instructions:
http://www.firebrandx.com/nespalette.html