Since I could not deduce whether UBS 2.0 or USB 3.0 abuts the spacebar, I bought and tested me.
When connected to a USB3.0 port is unfortunately not on the Geschwindgkeit to the USB port of 3.0.
Result:
directly USB3.0: approximately 75MB / s
on the spacebar: 40MB / s
Qualitatively, the stator is OK, but I would have wished for 85 USB3.0 already.
Update 22:01:15: had today unfortunately find that the left front ports do not go. Have been tested with iPhone, iPod, USB stick, unfortunately no response devices. USB Stick briefly light (2s) on, then off again.
Therefore, the stand goes back today and hope for compensation (in general I think the iMac quite well).
For the time being written down to 2 stars.
Update 01/25/15: Yesterday, spare :) now work all USB ports as described. Could I now make friends with the USB 2.0 version, since I still use another USB3.0 Hub. Still, I find the price for USB 2.0 bit overpriced, so I can only give 4 stars, but make a recommendation.
