Found Some info in the wiki;
"The OpenWrt buildroot generates images that can be directly flashed to the NS2, usually with a name like openwrt-atheros-ubnt2-squashfs.bin."
Sounds easy.
But I don't understand ;
"In order to upgrade from OpenWrt to a newer version, both the kernel mtd and filesystem mtd must be reflashed. The kernel is likely lzma compressed. If either mtd block isn't big enough, reflashing can not be completed through OpenWrt, but must be done through the RedBoot bootloader. "
Is this just saying the GUI won't, but Tftping to the device and reflashing will ?
The rollback described uses Tftp to recover back to their Air OS.
Guess I'm just being paranoid. I hate bricks ;o)