Gridseed 340 KH/s on Lightcoin Review:
In most cases we where getting at or above 300 KH/s during our testing of it for 60 days.
It can reach sucessful mining speeds without the higher cost of electricity per month nor the compareable higher initial cost of a high end video card.
This model generaly perform as promised, but not plug and play.
Expect some tweaking and adjustments to get it perfect.
But the tweaking and customizing is all part of the fun for Crypto-mining.