They don't substitute for Level II which gives an idea of support levels and maybe a guess if volume of trading likely to be high.

All I can see ahead is another low volume day, hopefully weak hands are out and we'll see higher asks.

The pre opening ask and offer we see are often messed about with by the brokers and they are vapourous in that they magically disappear a few minutes before trading starts.

If somebody got wind of a news release then yes you'd see some volotile movement really early. We don't expect any news but Richard has surprised people before now.