I have a nephew that works for the State of Illinois maintaining computers for a living.  he just visited last week and mentioned the subject of jump drives.  According to his experience, some who have depended only on jump drives for backup have lost their data sometimes.

Personally, I use them a lot to transfer data, haven't had a problem.  I backup to other computers on my personal network.

He says in his office, they use USB hard drives, large ones sell for around $200 now.  (I haven't priced one yet, just what he said.)  They back up the complete drive, and throw the USB hard drive in the bank lock box.  If it is good enough for the State of Illinois, I would think it would work for me, and I plan to look into the cost of buying a USB hard drive for that purpose.