Is a Thumb Drive Suitable for a Backup Drive?

I read a high capacity thumb drive can be used as effectively as an external hard drive (you recommended the seagate in your recommended products page). The article said you erase the ssd and reformat it to the apple os extended journal just as you would do with the seagate backup unit.
What do you think and would you recommend it? Samsung and Scandisc make a 128 GB and even higher capacity thumb drive. It sure would be easy to grab it and put it in your pocket in the case of an emergency.
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Mike Ritchie