Re: Is there a way to save a copy of your bottable usb drive?
Ok, I'm confused: You ask about copying USB to USB, but give a link to yet another backup utility for a Win box hard drive system.
So I'll give it a shot at untangling these two very different things
As to copying an install of Ubuntu to a USB thumb drive, with persistence, it's as simple as running the dd command:
where /dev/sdX is the device name of the "source" USB drive and /dev/sdY is the device name of the USB drive you wish to copy to. I said thumb drive above, that command will work on USB external hard drives - if you're patient. For 1, 2 4GB flash drives it completes reasonably quick (minutes). For a 1TB external - you'll be waiting hours.
dd if=/dev/sdX of=/dev/sdY
Note that you'll do this NOT from the flash drive, use a box with Ubuntu on it (or booted from a Live CD) and unmount both drives after you plug them in.
Note also the drive should be the same size as it's a byte for byte copy. Not that there's anything wrong with having a copy drive that's larger - obviously it can't be smaller - but for example a 2GB source copied to a 4GB will appear as a 2GB. You could reclaim the extra 2GB with gparted - but then it wouldn't be an exact copy.
As to backup solutions sporting USB boot recovery: I do exactly that via System Rescue CD (on a USB thumb drive) and use partimage to do a full backup to an external USB connected hard drive. An Ubuntu Live CD could also be used, I prefer the System Rescue CD because it's a Swiss Army Knife of system recovery tools, the Ubuntu Live CD is somewhat limited (can't run totally in RAM, for example).
Main system: Dell 1420n - C2D T5250, 4GB RAM, 120GB SATA. Ubuntu 8.04.3.
Assorted VMs (via VBox). Favorites: Fedora, FreeBSD, Solaris.