I have several.
They are great units. Easy to use and fun as well.
They are stable and run the best using MultiMiner with the BFGMiner dualminer pre-release.
I even did a review of them you can see here.
http://www.cryptocoinsnews.com/news/dualminer-sha-256-scrypt-usb-miner/2014/02/26The people from DualMiner are great to talk to and very responsive if you have questions.
I hope this helps you out.
Happy Mining.
Anyone using this, Is this miner a good buy
Hope you like it.