well it seems the later DIR-2660-A1's needs this as well
I think as some point they updated the boot loader
it would be better if this mod was added for all the devices
that is the one's built by SGE DIR-878,867,882,1960,2660 & others
it wasn't added due to it not being needed at the time
but it would help in future is someone writes the encrypt part
with would make them web flashable
you could contact them i think it would speed up everything
it would take me a long time to lean how & then another 6 mouths for the commit to got thought