I've made the first official cgminer release with support for these now (version 4.8.0). It is the same as the last binary I updated in performance but has some cosmetic improvements.

Note that these PSUs are VERY easy to destroy and I highly recommend people do not overvolt them with the provided PSU. Damaging the PSU will likely destroy the U3 as well. I'm not really sure where the fault lies but I suspect the PSUs are dodgy and if you have another power source, use that instead until bitmain can confirm whether there is an issue with the PSU. It wouldn't be the first device they've sold with a dodgy PSU.