Hi There,
You will not find any speed variance between the SB10 and the camera USB. You should expect to spend about 15-20 minutes per 16GB card. If you have some money you can get one of these
http://www.nextodi.com/en/product/NVS2500_en.html and back it up in 3 minutes. Of course for the same 2000 you could always get a Macbook Pro and back up via the express card slot as well as use the computer for other stuff.
I wish I was good at one thing rather than average at many, but oh well.