I'm getting really tired of the allegations against HFT (No, I'm not an HFTer but I do admire their technology..)....People complaining about HFT seeing data first is analogous to me complaining that common people in New York see data before I do in Arizona. Its just physics....light can only travel so fast. As for front running... most people I hear complain about their slippage are trading on bar data and are trying to capture pip sized moves in the stock.... what do you expect? If they would model their fills during backtest using tick data, I think they would have more realistic slippage expectations.