Sigma f/1.4 AF Issues

Hi,

I am trying to decide between the Canon 35mm L f/1.4 and the new Sigma 35 f/1.4.

One area the worries me about the Sigma is the rumor that the the AF is not as good as the Canon. Can any one supply and data and/or real world usage information to confirm/deny that this is an issue? I worry that this is simply a carry-over from people's previous experiences with Sigma lenses.

Thanks,

Tom