Although your settings are indicating a average hash rate of roughly 2.2 GH/s/unit your settings appear to be resulting in a fairly low efficiency (Efficiency defined as number of shares accepted (multiplied by their difficulty) per 2 KB of bandwidth) and a low percentage of accepted shares with a higher number of rejections than I have experienced. Although I readily got 2.2+ out of my U1's, it took some tweaking to actually get my U1's to perform where it counts. There's a difference of about 4+ GH/s there for your six units. That's like canning two units running at stock frequency.

You may want to start by trying to raise your worker difficulty from 8 to something a little higher.

FYI, I tried overclocking one of my U1's utilizing the resistor mod... I put a 10K 1% resistor in for R2 and a 3.74K 1% resistor in for R1 (both 0603 size).

Using bfgminer, I'm getting terrible hash rates now (and the unit gets much hotter...) doesn't seem like its doing much/anything. Not sure bfgminer is doing the right thing though, because regardless of what I set --set-device ant miner:clock= to, I can't really get (any of) my units to go above ~1.9Gh/s. Even at what should be higher clock rates, I get a pretty stable 1.9Gh/s and no errors. Any tips?

Thanks for the comments! I am really interested in trying to replace the resistors with the 4.99 and 10k and see what i can get it to.. with the du-orb on it stays really cool with the 09 setting with low hw errors in cgminer. I haven't tried bfgminer yet does it improve hw errors and oc stability at all?