Supremely interesting insight - it's now on my desktop.
The lesson i take from it is that big sites, run white hat, will win over small sites. A small site can so easily and innocently run into trouble. A large white hat site will smooth out any problem areas as far as G is concerned.
The problem for the committed small time guys like me who have only one "big time" site is how to protect yourself from that big time site falling foul of G. I did have a backup plan but the EMD update crucified that.
I have a couple of other sites which are OK but big sites seem to be the name of the game nowadays. This article makes me feel very, very vulnerable.