i have a few different backups, my main one that i always use is vix2.0, as i dont like all the bells and whistles in the newer images, but its only the last few months ive actually found this feature myself to be very handy.
i leave the backup itself on the usb stick thats always in the back of my duo, then i flash with anything and everything, ive even flashed with faulty images (while testing things) that have left the box unuseable. if i get to this state, i have my backup ready, and just reflash from usb, back up and running, from a total brick, in about 5 mins.
if i try an image out, and dont like it, i simply FTP into the receiver, navigate to the usb in the back, get my backup, and flash again