Benchmarking USB drives

So I have several USB drives lying around and I realized that I am not really sure which one performs the best.  So I decided to benchmark them.

Patriot "Razzo" 8 GB:

OCZ Rally 2 4GB:

SD Cruzer 16 GB:

And for the heck of it, here is a 500 GB Western Digital USB hard drive (not solid state):

Some observations:

It would seem that 32.77 MB/s read speed result may be limited by the USB2 bus speed, and not by the memory stick itself.  I base this off of the fact that two USB sticks are getting similar read results which I do not think is a coincidence.

Also, the 16 GB version is quite a bit slower.  I've noticed that solid state memory in greater capacities (such as on SD cards) tends to perform slower so this backs up my findings.

Guess I will be using that Patriot stick for the time being!