I just became aware of a tool, DumpFlash, by Jeong Wook:
DumpFlash is a tool to retrieve and write Flash data to the physical NAND Flash memory or virtual image file. Various operations like ECC check and on-image pattern recognition, extraction and rewriting for u-Boot bootloader and JFFS2 file system are supported.
https://github.com/ohjeongwook/DumpFlash
Click to access us-14-Oh-Reverse-Engineering-Flash-Memory-For-Fun-And-Benefit.pdf
Click to access Reverse%20Engineering%20Flash%20Memory%20for%20Fun%20And%20Benefit.pdf
DumpFlash aside, also check out his DaruGrim tool, a Binary Diffing and Patch Analysis Tool:
Firmware Security 