My apologies for the late reply. Some IRL familiy stuff happened.
I see now that I forgot to mention that I was running cgminer and bfgminer on Windows 10.
The unit did not come with a PSU. Perhaps the previous owner kept it. At first I attempted several PC PSU's that I had lying around (CoolerMaster, Corsair, Antec varying between 400W and 850W), but had no luck with those.
Ultimately, I lend the U3 to a friend for a couple of days and he had no trouble getting it to run on Debian. He returned the unit last weekend and I had some time today to tinker with it some more. I bought a Pi2 and a 120W PSU, just now installed Raspbian and I got running within 20 minutes using cgminer.
I'm happy that it runs, but I still have no clue where I went wrong with the Windows versions of cgminer and bfgminer. I did use Zadig to replace the driver, but perhaps it was still a driver issue?
Thanks again.
It's hard to say some they load zadig once... and no issues works great. Others it's one of the most painful driver installs they will have.
I think you will be much happier with the RPI then you were on windows. It is also a low power controller which is great. I think long term you made a good decision. As you can always use the RPI for tons of projects one day after done mining with it.