From CGMiner readme:
U: The Utility defined as the number of shares / minute
WU: The Work Utility defined as the number of diff1 shares work / minute
(accepted or rejected).
Doesn't seem like WU is the hash that you "throw away for nothing"

Edit: I just checked several pools and it was all pretty much the same, even Middlecoin. Might just be the coin we are mining now, though? My hashrate is 750KH/s and the WU value was between 660-730. Middlecoin was right around 710-720.
About the difficulty, I know what's right, and what's not. It's fine if people discuss it, because that will help bring them closer to the truth.
Just tell me I am right and give us a status update on diverting the hashrate to multiple coins
