If I plug a USB 3 stick (with 20/60MBps write/read speed) into a USB 2 port is it possible to get this speed (because USB 2 should be able to get 480Mbps = 60MBps)?
I would assume that this speed could be handled if nothing else interferes (like other USB devices on the same controller or something like that).
No. Like humanityANDpeace's comment states, 20 MBps is around the best you will get from USB 2.0 in practice. This is also what I have experienced using various hardware. It's simply the limitation of the interface; plugging in a USB 3.0 stick will not suddenly upgrade your interface.
Wikipedia states the following:
Released in April 2000. Added higher maximum signaling rate of 480 Mbit/s (effective throughput up to 35 MB/s or 280 Mbit/s)
Personally, I can't recall achieving 35 MBps, but it is not inconceivable with certain configurations.
