so I'm thinking of only buying usb 3.0 flash drives. I'm guessing that even with a USB 2.0 computer usb 3.0 flash drives would be faster, hopefully getting class 10 or better speeds because the manufacturers wont use slower flash ram inside. Am I right?
10MB/s sequential write speed (on a USB 2.0 port) is actually pretty easy to achieve for most decent USB 3.0 flash drives. In my experience, you can expect somewhere around 75-80% of the rated write speed (provided that it's below the USB 2.0 theoretical ceiling of 60MB/s).
I regularly see around 14-15MB/s writes with my wife's USB 3.0 flash drive (Lexar S73 16GB). I haven't tried using my SanDisk Extreme 32GB on a USB 2.0 port yet, will try it out tonight when I get home and post the results here. :-)