Speed USB 3.0 is good to go with me at a maximum of just under 90-100MB / s write (about 500MB more large files) - slightly slower than the hard drive could, but still perfectly fine.
The clone function I have not tested it, but I also NEN very nice touch.
Incidentally, you put a second hard drive while running operation to an already added in current, connect the USB briefly separated. So when copying data better not a hard drive to insert / remove, as this also the connection to the other plate is briefly interrupted.