Here is my updated string:
bfgminer.exe -S amu:all --set-device antminer:clock=x0781 --no-submit-stale -o stratum+tcp://stratum.btcguild.com:3333 -O xxxx_2
Once launched, I manually changed the S to 30, E to 60 and Q to 15 like your example. For some reason, it rejected those settings from the command line.
Now, I'm getting around 1.5Gh/s, but I still can't get higher. If I change from 0781 to 0881, 0981, or 0A81, my Gh/s rate in the third column drops to 0. Obviously 1.5Gh/s is much better than I was getting, so I'm happier, but I'd love to figure out why I'm still not getting 2.0Gh/s like the U2 is supposed to be capable of.
Also, I noticed in your screenshot that the A: value is always 0 or 1, but mine is A: 34 at the time of this screenshot and climbing every few seconds. What does this value mean?
Finally, you asked about my USB connections. Right now, I'm not using any hubs, splitter, cables, etc. I'm plugging directly into an on-board USB port.
http://i.imgur.com/JISQcbO.jpg