It appears that my semi-direct path is to get to the newest [MINUS 1] version of 4.2.1 from Asus.
Many newer ROMS require this boot loader, and many people say to stick with the twrp 184.108.40.206 because 2.6.x.x is buggy. I can confirm that 2.6.x.x (latest), the mount feature does appear to be broken.
My only concern now is timing. Upgrade to 220.127.116.11 first, or upgrade using fastboot to the new Asus rom. It might not matter and I might need to put TRWP back on after the flash anyhow.
Also, I did root my current OS before doing this update, so it will be interesting to see if that remains intact.