Usb sticks fail often, but not the CF cards I use intensively, so
- Take CF, not Usb sticks
- It's not related with Flash technology
Intel gives several years life expectancy at 1GB/hour write rate for its Flash SSD. Just try to write as much on a mechanical disk: it will fail much earlier.
You may try the DisableNtfsLastAccessUpdate in the registry. It reduces the number of writes to the disk, which also improves speed on older Flash disks. And of course, use Xp's improved write filter, and align the volumes.
Anyway, a 4GB drive is cheap now, so use it, backup, and observe.